|                                                                                                                                                                                    | **United                  States**                                                                                                              |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------|
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    | **Securities                  and Exchange Commission**                                                                                         |
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    | **Washington,                  D.C. 20549**                                                                                                     |
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    | **Form                  10 QSB**                                                                                                                |
|                                                                                                                                                                                    |                                                                                                                                            |
| (Mark                  One)                                                                                                                                                             |
|                                                                                                                                                                                    |                                                                                                                                            |
| **R**                                                                                                                                                                                   | **QUARTERLY                  REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE                  ACT OF                  1934** |
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    | For                  the quarterly period ended June 30, 2007                                                                                   |
|                                                                                                                                                                                    |                                                                                                                                            |
| o                                                                                                                                                                                       | **TRANSITION                  REPORT UNDER SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE ACT                  OF                  1934**      |
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    | For                  the transition period from _____ to _____                                                                                  |
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    | Commission                  file number 333-105811                                                                                              |
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    | **ATLAS                  AMERICA PUBLIC #12-2003 Limited Partnership**                                                                          |
|                                                                                                                                                                                    | (Name                  of small business issuer in its charter)                                                                                 |
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    |                                                                                                                                            |
|                                                                                                                                                                                    |                                                                                                                                            |
| **Delaware**                                                                                                                                                                            | **54-2113989**                                                                                                                                  |
| (State                  or other jurisdiction ofincorporation                  or organization)                                                                                         | (I.R.S.                  EmployerIdentification                  No.)                                                                           |
|                                                                                                                                                                                    |                                                                                                                                            |
| Westpointe                  Corporate Center One                                                                                                                                        |                                                                                                                                            |
| 1550                  Coraopolis Heights Road, 2nd Floor                                                                                                                                |                                                                                                                                            |
| Moon                  Township, PA                                                                                                                                                      | 15108                                                                                                                                           |
| (Address                  of principal executive offices)                                                                                                                               | (zip                  code)                                                                                                                     |
|                                                                                                                                                                                    |                                                                                                                                            |
| Issuer’s                  telephone number, including area code: **(412)                  262-2830**                                                                              |
|                                                                                                                                                                                    |
| Indicate                  by check mark whether the registrant (1) filed all reports required                  to be                  filed by Section 13 or 15 (d) of the Exchange Act |
| during                  the past 12 months (or for such shorter period that the registrant                  was                  required to file such reports),                        |
| and                  (2) has been subject to such filing requirements for the past 90                  days.                  Yes** ****R**                  No o                  |
|                                                                                                                                                                                    |
| Indicate                  by check mark whether the registrant is a shell company (as defined                  in                  Rule 12b-2 of the Exchange                           |
| Act).Yes                  o                  No **R**                                                                                                                                   |
|                                                                                                                                                                                    |
| Transitional                  Small Business Disclosure Format (check one): Yes o                  No **R**                                                                             |

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**(A        Delaware Limited Partnership)**

**INDEX        TO QUARTERLY REPORT**

**ON        FORM 10-QSB**

| **PART                  I.**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |   | **FINANCIAL                  INFORMATION**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | **PAGE** |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|----------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
| Item                  1:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   | Financial                  Statements                                                                                                                                                          |     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   | Balance                  Sheets as of June 30, 2007 and December 31,                  2006                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               | 3        |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   | Statements                  of Net Earnings for the Three Months and Six Months Ended June                  30, 2007                  and 2006                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | 4        |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   | Statement                  of Partners’ Capital Accounts for the Six Months ended June 30,                  2007                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    | 5        |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   | Statements                  of Cash Flows for the Six Months ended June 30, 2007 and                  2006                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                | 6        |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   | Notes                  to Financial                  Statements                                                                                                                                | 7-12     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
| Item                  2:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   | Management’s                  Discussion and Analysis of Financial Condition or Plan of                  Operations                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 | 13-17    |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
| Item                  3:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   | Controls                  and                  Procedures                                                                                                                                      | 17       |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
| **PART                  II.**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |   | **OTHER                  INFORMATION**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
| Item                  6:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   | Exhibits                                                                                                                                                                                       | 17       |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
| **SIGNATURES                                                                                                                                                   **     | 18     |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |     |
| **CERTIFICATIONS                                                                                                                                                   ** | 19-22  |

**PART        I**

**ITEM        1.                        FINANCIAL        STATEMENTS**

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**BALANCE        SHEETS**

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   | **June                  30,** |       |   | **December                  31,** |   |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-------------------------------|------------|--------|-----------------------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   | **2007**                      |       |   | **2006**                          |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   | **(Unaudited)**               |       |   | **(Audited)**                     |   |
| **ASSETS**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |                          |       |   |                              |   |
| Current                  Assets:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |   |                          |       |   |                              |   |
| Cash                  and cash                  equivalents                                                                                                                  |   | $                             | 1,809,200  |   |                              | $      | 1,041,200 |   |
| Accounts                  receivable-affiliate                                                                                                                               |   |                          | 311,000    |   |                              |   | 1,319,600 |   |
| Short-term                  hedge receivable due from                  affiliate                                                                                             |   |                          | 536,200    |   |                              |   | 1,176,900 |   |
| Total                  current                  assets                                                                                                                                                               |   |                          | 2,656,400  |   |                              |   | 3,537,700 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   |                          |       |   |                              |   |   |   |
| Oil                  and gas properties,                  net                                                                                                                |   |                          | 31,647,000 |   |                              |   | 33,479,600 |   |
| Long-term                  hedge receivable due from                  affiliate                                                                                              |   |                          | 282,600    |   |                              |   | 1,016,100 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   | $                             | 34,586,000 |   |                              | $      | 38,033,400 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   |                          |       |   |                              |   |   |   |
| **LIABILITIES                  AND PARTNERS’ CAPITAL**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |                          |       |   |                              |   |   |   |
| Current                  liabilities:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |   |                          |       |   |                              |   |   |   |
| Accrued                  liabilities                                                                                                                                         |   | $                             | 7,300      |   |                              | $      | 18,000 |   |
| Short-term                  hedge liability due to                  affiliate                                                                                                |   |                          | 53,900     |   |                              |   | 7,300 |   |
| Total                  current                  liabilities                                                                                                                                                          |   |                          | 61,200     |   |                              |   | 25,300 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   |                          |       |   |                              |   |   |   |
| Asset                  retirement                  obligation                                                                                                                |   |                          | 2,008,000  |   |                              |   | 1,949,500 |   |
| Long-term                  hedge liability due to                  affiliate                                                                                                 |   |                          | 629,900    |   |                              |   | 163,500 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   |                          |       |   |                              |   |   |   |
| Partners’                  capital:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |   |                          |       |   |                              |   |   |   |
| Managing                  general                  partner                                                                                                                   |   |                          | 9,826,000  |   |                              |   | 10,158,200 |   |
| Limited                  partners (4,024.15                  units)                                                                                                          |   |                          | 22,051,800 |   |                              |   | 23,908,300 |   |
| Accumulated                  other comprehensive                  income                                                                                                     |   |                          | 9,100      |   |                              |   | 1,828,600 |   |
| Total                  partners'                  capital                                                                                                                                                            |   |                          | 31,886,900 |   |                              |   | 35,895,100 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   | $                             | 34,586,000 |   |                              | $      | 38,033,400 |   |

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**STATEMENTS        OF NET EARNINGS**

**(Unaudited)**

|                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   | **Three                  Months Ended** |      |   | **Six                  Months Ended** |   |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------------------|-----------|--------|---------------------------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   | **June                  30,**           |      |   | **June                  30,**         |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   | **2007**                                |      |   | **2006**                              |   |   | **2007** |   |   | **2006** |   |
| **REVENUES:**                                                                                                                                                                                                                                                                                                                                                                                                                                          |   |                                    |      |   |                                  |   |   |   |   |   |   |   |
| Natural                  gas and                  oil                                                                       |   | $                                       | 1,564,600 |   |                                  | $      | 2,137,400 |   |   | $ | 3,374,300 |   |   | $ | 5,089,900 |   |
| Interest                  income                                                                                            |   |                                    | 12,400    |   |                                  |   | 14,500 |   |   |   | 21,600 |   |   |   | 28,600 |   |
| Total                  revenues                                                                                                                                     |   |                                    | 1,577,000 |   |                                  |   | 2,151,900 |   |   |   | 3,395,900 |   |   |   | 5,118,500 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   |                                    |      |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| **COSTS                  AND EXPENSES:**                                                                                                                                                                                                                                                                                                                                                                                                               |   |                                    |      |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| Production                                                                                                                  |   |                                    | 466,500   |   |                                  |   | 519,700 |   |   |   | 893,000 |   |   |   | 956,800 |   |
| Depletion                                                                                                                   |   |                                    | 841,700   |   |                                  |   | 844,800 |   |   |   | 1,832,600 |   |   |   | 1,907,400 |   |
| Accretion                  of asset retirement obligation                                                                                                                                                                                                                                                                                                                                                                                              |   |                                    | 29,300    |   |                                  |   | 29,000 |   |   |   | 58,500 |   |   |   | 58,000 |   |
| General                  and                  administrative                                                                |   |                                    | 51,900    |   |                                  |   | 58,800 |   |   |   | 108,800 |   |   |   | 113,500 |   |
| Total                  expenses                                                                                                                                     |   |                                    | 1,389,400 |   |                                  |   | 1,452,300 |   |   |   | 2,892,900 |   |   |   | 3,035,700 |   |
| **Net                  earnings                                                               **                            |   | $                                       | 187,600   |   |                                  | $      | 699,600 |   |   | $ | 503,000 |   |   | $ | 2,082,800 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   |                                    |      |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| **Allocation                  of net (loss) earnings:**                                                                                                                                                                                                                                                                                                                                                                                                |   |                                    |      |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| Managing                  general                  partner                                                                  |   | $                                       | 264,900   |   |                                  | $      | 450,700 |   |   | $ | 609,900 |   |   | $ | 1,193,600 |   |
| Limited                  partners                                                                                           |   | $                                       | (77,300   | )      |                                  | $      | 248,900 |   |   | $ | (106,900 | ) |   | $ | 889,200 |   |
| Net                  (loss) earnings per limited partnership unit                                                                                                                                                                                                                                                                                                                                                                                      |   | $                                       | (20       | )      |                                  | $      | 62 |   |   | $ | (27 | ) |   | $ | 221 |   |

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**STATEMENT        OF PARTNERS’ CAPITAL ACCOUNTS**

**FOR        THE SIX MONTHS ENDED June 30, 2007**

**(Unaudited)**

|                                                                                                                                                                                                                                                                                                                                                                                                                               |   |         |       |   |         |   |       | **Accumulated**                    |   |   |       |   |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|--------------|------------|--------|--------------|--------|------------|------------------------------------|--------|--------|------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   | **Managing** |       |   |         |   |       | **Other**                          |   |   |       |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   | **General**  |       |   | **Limited**  |   |       | **Comprehensive**                  |   |   |       |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   | **Partner**  |       |   | **Partners** |   |       | **Income                  (loss)** |   |   | **Total**  |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   |         |       |   |         |   |       |                               |   |   |       |   |
| **Balance                  at January 1, 2007**                                                                                                                                                                                                                                                                                                                                                                                    |   | $            | 10,158,200 |   |         | $      | 23,908,300 |                               |   | $      | 1,828,600  |   |   | $ | 35,895,100 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   |         |       |   |         |   |       |                               |   |   |       |   |   |   |   |   |
| Participation                  in revenues and expenses:                                                                                                                                                                                                                                                                                                                                                                           |   |         |       |   |         |   |       |                               |   |   |       |   |   |   |   |   |
| Net                  production                  revenues                                                                                       |   |         | 868,500    |   |         |   | 1,612,800  |                               |   |   | —    |   |   |   | 2,481,300 |   |
| Interest                  income                                                                                                                |   |         | 7,500      |   |         |   | 14,100     |                               |   |   | —    |   |   |   | 21,600 |   |
| Depletion                                                                                                                                       |   |         | (207,500   | )      |         |   | (1,625,100 | )                                  |   |   | —    |   |   |   | (1,832,600 | ) |
| Accretion                  of asset retirement obligation                                                                                                                                                                                                                                                                                                                                                                          |   |         | (20,500    | )      |         |   | (38,000    | )                                  |   |   | —    |   |   |   | (58,500 | ) |
| General                  and                  administrative                                                                                    |   |         | (38,100    | )      |         |   | (70,700    | )                                  |   |   | —    |   |   |   | (108,800 | ) |
| Net                  earnings                  (loss)                                                                                                                    |   |         | 609,900    |   |         |   | (106,900   | )                                  |   |   | —    |   |   |   | 503,000 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   |         |       |   |         |   |       |                               |   |   |       |   |   |   |   |   |
| Other                  comprehensive                  loss                                                             |   |         | —    |   |         |   | —    |                               |   |   | (1,819,500 | )      |   |   | (1,819,500 | ) |
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   |         |       |   |         |   |       |                               |   |   |       |   |   |   |   |   |
| Distributions                  to                  partners                                                                                     |   |         | (942,100   | )      |         |   | (1,749,600 | )                                  |   |   | —    |   |   |   | (2,691,700 | ) |
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   |         |       |   |         |   |       |                               |   |   |       |   |   |   |   |   |
| **Balance                  at June 30, 2007**                                                                                                                                                                                                                                                                                                                                                                                      |   | $            | 9,826,000  |   |         | $      | 22,051,800 |                               |   | $      | 9,100      |   |   | $ | 31,886,900 |   |

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**STATEMENTS        OF CASH FLOWS**

**(Unaudited)**

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   | **Six                  Months Ended** |       |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|---------------------------------------|------------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   | **June                  30,**         |       |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   | **2007**                              |       |   | **2006** |   |
| **Cash                  flows from operating activities:**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |   |                                  |       |   |   |   |
| Net                  earnings                                                                                                                                                                                                                                                      |   | $                                     | 503,000    |   |   | $ | 2,082,800 |   |
| Adjustments                  to reconcile net earnings to net cash provided by operating                  activities:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   |                                  |       |   |   |   |   |   |
| Depletion                                                                                                                                                                                                                        |   |                                  | 1,832,600  |   |   |   | 1,907,400 |   |
| Non-cash                  loss on derivative                  value                                                                                                                                                              |   |                                  | 67,700     |   |   |   | — |   |
| Accretion                  of asset retirement                  obligation                                                                                                                                                       |   |                                  | 58,500     |   |   |   | 58,000 |   |
| Decrease                  in accounts receivable –                  affiliate                                                                                                                                              |   |                                  | 1,008,600  |   |   |   | 1,300,000 |   |
| Decrease                  in accrued                  liabilities                                                                                                                                                                |   |                                  | (10,700    | ) |   |   | (20,900 | ) |
| Net                  cash provided by operating                  activities                                                                                                                        |   |                                  | 3,459,700  |   |   |   | 5,327,300 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |                                  |       |   |   |   |   |   |
| **Cash                  flows from investing activities:**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |   |                                  |       |   |   |   |   |   |
| Proceeds                  from asset                  sale                                                                                                                                         |   |                                  | —    |   |   |   | 1,200 |   |
| Purchase                  of tangible                  equipment                                                                                                                                   |   |                                  | —    |   |   |   | (15,800 | ) |
| Net                  cash used in investing                  activities                                                                                                                            |   |                                  | —    |   |   |   | (14,600 | ) |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |                                  |       |   |   |   |   |   |
| **Cash                  flows from financing activities:**                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |   |                                  |       |   |   |   |   |   |
| Distributions                  to                  partners                                                                                                                                        |   |                                  | (2,691,700 | ) |   |   | (5,806,000 | ) |
| Net                  cash used in financing                  activities                                                                                                                            |   |                                  | (2,691,700 | ) |   |   | (5,806,000 | ) |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |   |                                  |       |   |   |   |   |   |
| Net                  increase (decrease) in cash and cash                  equivalents                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |   |                                  | 768,000    |   |   |   | (493,300 | ) |
| Cash                  and cash equivalents at beginning of                  period                                                                                                                 |   |                                  | 1,041,200  |   |   |   | 1,938,700 |   |
| Cash                  and cash equivalents at end of                  period                                                                                                                       |   | $                                     | 1,809,200  |   |   | $ | 1,445,400 |   |

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**NOTES        TO FINANCIAL STATEMENTS**

**June        30, 2007**

**(Unaudited)**

**NOTE        1 - DESCRIPTION        OF BUSINESS**

**NOTE        2 - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES**

**Use        of Estimates**

**Receivables**

**Revenue        Recognition**

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**NOTES        TO FINANCIAL STATEMENTS (Continued)**

**June        30, 2007**

**(Unaudited)**

**NOTE        2 - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Continued)**

**Asset        Retirement Obligation**

*Accounting for Asset Retirement        Obligations*
*, Accounting for Conditional Asset Retirement        Obligations.*

|                                                                                                                                                                                                                                                                                                                                                                                                                               |   | **Three                  Months Ended** |      |   | **Six                  Months Ended** |   |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------------------|-----------|--------|---------------------------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   | **June                  30,**           |      |   | **June                  30,**         |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   | **2007**                                |      |   | **2006**                              |   |   | **2007** |   |   | **2006** |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                               |   |                                    |      |   |                                  |   |   |   |   |   |   |   |
| Asset                  retirement obligation at beginning of period                                                                                                                                                                                                                                                                                                                                                                |   | $                                       | 1,978,700 |   |                                  | $      | 1,923,900 |   |   | $ | 1,949,500 |   |   | $ | 1,894,900 |   |
| Accretion                  expense                                                                 |   |                                    | 29,300    |   |                                  |   | 29,000 |   |   |   | 58,500 |   |   |   | 58,000 |   |
| Asset                  retirement obligation at end of period                                                                                                                                                                                                                                                                                                                                                                      |   | $                                       | 2,008,000 |   |                                  | $      | 1,952,900 |   |   | $ | 2,008,000 |   |   | $ | 1,952,900 |   |

**Property        and Equipment**

| Oil                  and gas properties consist of the following at the dates                  indicated:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   | **June                  30,** |        |   | **December                  31,** |   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-------------------------------|-------------|--------|-----------------------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   | **2007**                      |        |   | **2006**                          |   |
| Mineral                  interest in properties:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |   |                          |        |   |                              |   |
| Proved                  properties                                                                                                                                            |   | $                             | 1,169,700   |   |                              | $      | 1,169,700 |   |
| Wells                  and related                  equipment                                                                                                                 |   |                          | 49,132,700  |   |                              |   | 49,132,700 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   |                          | 50,302,400  |   |                              |   | 50,302,400 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   |                          |        |   |                              |   |   |   |
| Accumulated                  depletion of oil and gas                  properties                                                                                             |   |                          | (18,655,400 | )      |                              |   | (16,822,800 | ) |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |   | $                             | 31,647,000  |   |                              | $      | 33,479,600 |   |

**Recently        Issued Financial Accounting Standards**

*Offsetting of Amounts Related to Certain Contracts*

*The Fair Value Option for Financial        Assets and Financial Liabilities.  *

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**NOTES        TO FINANCIAL STATEMENTS (Continued)**

**June        30, 2007**

**(Unaudited)**

**NOTE        2 - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Continued)**

*Fair Value        Measurement.  *

**NOTE        3 -        TRANSACTIONS WITH ATLAS RESOURCES, LLC AND ITS AFFILIATES**

| ·   | Administrative                  costs which are included in general and administrative expenses                  in the                  Partnership’s Statements of Net Earnings are payable at $75 per well per                  month.  Administrative costs incurred for the three months and                  six months ended June 30, 2007 were $45,200 and $90,700,                  respectively.  Administrative costs incurred for the three                  months and six months ended June 30, 2006 were $45,800 and $91,600,                  respectively. |
|--------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Monthly                  well supervision fees which are included in production expenses                  in the                  Partnership’s Statements of Net Earnings are currently payable at $301 per                  well per month for operating and maintaining the wells.  Well                  supervision fees incurred for the three months and six months ended                  June                  30, 2007 were $181,600 and $364,400, respectively.  Well                  supervision fees incurred for the three months and six months ended                  June                  30, 2006 were $173,600 and $341,600,                  respectively. |
|--------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Transportation                  fees which are included in production expenses in the Partnership’s                  Statements of Net Earnings are payable at rates ranging from $.29-$.35                  per                  one thousand cubic feet ("Mcf") to 13% of the natural gas sales                  price.  Transportation fees incurred for the three months and                  six months ended June 30, 2007 were $201,000 and $395,200,                  respectively.  Transportation fees incurred for the three months                  and six months ended June 30, 2006 were $257,900 and $446,500,                  respectively. |
|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

**Subordination        by Managing General Partner**

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**NOTES        TO FINANCIAL STATEMENTS (Continued)**

**June        30, 2007**

**(Unaudited)**

**NOTE        4 – COMPREHENSIVE INCOME**

|                                                                                                                                                                                                                                                                                                                                                                                                                                  |   | **Three                  Months Ended** |     |   | **Six                  Months Ended** |   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------------------|----------|--------|---------------------------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                  |   | **June                  30,**           |     |   | **June                  30,**         |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                  |   | **2007**                                |     |   | **2006**                              |   |   | **2007** |   |   | **2006** |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                  |   |                                    |     |   |                                  |   |   |   |   |   |   |   |
| Net                  earnings                                                                                             |   | $                                       | 187,600  |   |                                  | $      | 699,600 |   |   | $ | 503,000 |   |   | $ | 2,082,800 |   |
| Other                  comprehensive (loss) income:                                                                                                                                                                                                                                                                                                                                                                                   |   |                                    |     |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| Unrealized                  holding gain (loss) on hedging contracts                                                                                                                                                                                                                                                                                                                                                                  |   |                                    | 293,700  |   |                                  |   | 696,900 |   |   |   | (1,491,400 | ) |   |   | 1,318,500 |   |
| Less:                  reclassification adjustment for gains realized in net                  earnings                                                                                                                                                                                                                                                                                                                                |   |                                    | (149,700 | )      |                                  |   | (201,900 | ) |   |   | (328,100 | ) |   |   | (363,000 | ) |
|                                                                                                                                                                                                                                                                                                                                                                                                                                  |   |                                    | 144,000  |   |                                  |   | 495,000 |   |   |   | (1,819,500 | ) |   |   | 955,500 |   |
| Comprehensive                  income                  (loss)                                                             |   | $                                       | 331,600  |   |                                  | $      | 1,194,600 |   |   | $ | (1,316,500 | ) |   | $ | 3,038,300 |   |

**NOTE        5 – DERIVATIVE INSTRUMENTS**

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**NOTES        TO FINANCIAL STATEMENTS (Continued)**

**June        30, 2007**

**(Unaudited)**

**NOTE        5 – DERIVATIVE INSTRUMENTS (Continued)**

| **Fixed                  Price Swaps** |                               |   |                             |    |   |                             |                             |   |                            |       |
|----------------------------------------|------------------------------------|--------|----------------------------------|---------|--------|----------------------------------|----------------------------------|--------|---------------------------------|------------|
|                                   |                               |   |                             |    |   |                             |                             |   | **Fair                  Value** |       |
|                                   | **Twelve                  Month**  |   | **Volumes**                      |    |   | **Average**                      |                             |   | **Asset**                       |       |
|                                   | **Period                  Ending** |   | **(per                  MMBTU)** |    |   | **Fixed                  Price** |                             |   | **(Liability)**                 |       |
|                                   | **June                  30,**      |   | ** **                       | **(1)** |   |                             | **(per                  MMBTU)** |   |                            | ** ** | **(2)** |   |
|                                   |                               |   |                             |    |   |                             |                             |   |                            |       |   |   |
|                                   | 2008                               |   |                             | 573,300 |   |                             | $                                | 8.682  |                            |       | $ | 472,300 |   |
|                                   | 2009                               |   |                             | 560,600 |   |                             | $                                | 8.533  |                            |       |   | (3,400 | ) |
|                                   | 2010                               |   |                             | 434,100 |   |                             | $                                | 8.053  |                            |       |   | (133,600 | ) |
|                                   | 2011                               |   |                             | 242,400 |   |                             | $                                | 7.524  |                            |       |   | (132,700 | ) |
|                                   | 2012                               |   |                             | 84,300  |   |                             | $                                | 7.365  |                            |       |   | (33,500 | ) |
|                                   |                               |   |                             |    |   |                             |                             |   |                            |       | $ | 169,100 |   |

**ATLAS        AMERICA PUBLIC #12-2003 Limited Partnership**

**NOTES        TO FINANCIAL STATEMENTS (Continued)**

**June        30, 2007**

**(Unaudited)**

**NOTE        5 – DERIVATIVE INSTRUMENTS (Continued)**

| **Costless                  Collars** |                               |                            |   |                             |    |   |                                 |                             |   |                            |       |
|---------------------------------------|------------------------------------|---------------------------------|--------|----------------------------------|---------|--------|--------------------------------------|----------------------------------|--------|---------------------------------|------------|
|                                  |                               |                            |   |                             |    |   |                                 |                             |   | **Fair                  Value** |       |
| **Company**                           | **Twelve                  Month**  |                            |   | **Volumes**                      |    |   | **Average**                          |                             |   | **Asset**                       |       |
|                                  | **Period                  Ending** | **Option**                      |   | **(per                  MMBTU)** |    |   | **Floor                  & Cap** |                             |   | **(Liability)**                 |       |
|                                  | **June                  30,**      | **Type**                        |   | ** **                       | **(1)** |   |                                 | **(per                  MMBTU)** |   |                            | ** ** | **(2)** |   |
|                                  |                               |                            |   |                             |    |   |                                 |                             |   |                            |       |   |   |
|                                  | 2008                               | Puts                  purchased |   |                             | 31,600  |   |                                 | $                                | 7.500  |                            |       | $ | 13,500 |   |
|                                  | 2008                               | Calls                  sold     |   |                             | 31,600  |   |                                 | $                                | 8.600  |                            |       |   | — |   |
|                                  | 2008                               | Puts                  purchased |   |                             | 27,400  |   |                                 | $                                | 7.500  |                            |       |   | — |   |
|                                  | 2008                               | Calls                  sold     |   |                             | 27,400  |   |                                 | $                                | 9.400  |                            |       |   | (3,500 | ) |
|                                  | 2009                               | Puts                  purchased |   |                             | 27,400  |   |                                 | $                                | 7.500  |                            |       |   | — |   |
|                                  | 2009                               | Calls                  sold     |   |                             | 27,400  |   |                                 | $                                | 9.400  |                            |       |   | (3,900 | ) |
|                                  | 2010                               | Puts                  purchased |   |                             | 50,600  |   |                                 | $                                | 7.750  |                            |       |   | — |   |
|                                  | 2010                               | Calls                  sold     |   |                             | 50,600  |   |                                 | $                                | 8.750  |                            |       |   | (13,000 | ) |
|                                  | 2011                               | Puts                  purchased |   |                             | 50,600  |   |                                 | $                                | 7.750  |                            |       |   | — |   |
|                                  | 2011                               | Calls                  sold     |   |                             | 50,600  |   |                                 | $                                | 8.750  |                            |       |   | — |   |
|                                  | 2011                               | Puts                  purchased |   |                             | 126,500 |   |                                 | $                                | 7.500  |                            |       |   | — |   |
|                                  | 2011                               | Calls                  sold     |   |                             | 126,500 |   |                                 | $                                | 8.450  |                            |       |   | (30,000 | ) |
|                                  | 2012                               | Puts                  purchased |   |                             | 126,400 |   |                                 | $                                | 7.500  |                            |       |   | 2,800 |   |
|                                  | 2012                               | Calls                  sold     |   |                             | 126,400 |   |                                 | $                                | 8.450  |                            |       |   | — |   |
|                                  |                               |                            |   |                             |    |   |                                 |                             |   |                            |       | $ | (34,100 | ) |
|                                  |                               |                            |   |                             |    |   |                                 |                             |   |                            |       |   |   |   |
|                                  |                               |                            |   |                             |    |   |                                 | Net                  Asset       |   |                            | $          | 135,000 |   |

| (1)   | MMBTU                  represents million British Thermal                  Units. |
|-----------------|-----------------------------------------------------------------------------------|

| (2)   | Fair                  value based on forward NYMEX natural gas                  prices. |
|-----------------|-----------------------------------------------------------------------------------------|

|                                                                                                                                                                                                                                                                                                            |   | **June                  30, 2007** |     |   | **December                  31, 2006** |   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|------------------------------------|----------|--------|----------------------------------------|--------|
|                                                                                                                                                                                                                                                                                                            |   | **Book                  Value**    |     |   | **Fair                  Value**        |   |   | **Book                  Value** |   |   | **Fair                  Value** |   |
| Assets                                                                                                                                                                                                                                                                                                          |   |                               |     |   |                                   |   |   |   |   |   |   |   |
| Derivative                  instruments                                             |   | $                                  | 818,800  |   |                                   | $      | 818,800 |   |   | $ | 2,193,000 |   |   | $ | 2,193,000 |   |
|                                                                                                                                                                                                                                                                                                            |   | $                                  | 818,800  |   |                                   | $      | 818,800 |   |   | $ | 2,193,000 |   |   | $ | 2,193,000 |   |
| Liabilities                                                                                                                                                                                                                                                                                                     |   |                               |     |   |                                   |   |   |   |   |   |   |   |   |   |   |   |
| Derivative                  instruments                                             |   | $                                  | (683,800 | )      |                                   | $      | (683,800 | ) |   | $ | (170,800 | ) |   | $ | (170,800 | ) |
|                                                                                                                                                                                                                                                                                                            |   | $                                  | 135,000  |   |                                   | $      | 135,000 |   |   | $ | 2,022,200 |   |   | $ | 2,022,200 |   |

**ITEM        2.  MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION OR        PLAN OF OPERATIONS (UNAUDITED)**

**Forward-Looking        Statements**

*The        matters discussed within this report include forward-looking statements.        These        statements may be identified by the use of forward-looking terminology such        as“anticipate,” “believe,” “continue,” “could,” “estimate,” “expect,” “intend,”“may,” “might,” “plan,” “potential,” “predict,” “should,” or “will,” or the        negative thereof or other variations thereon or comparable terminology. In        particular, statements about our expectations, beliefs, plans, objectives,        assumptions or future events or performance contained in this report are        forward-looking statements. We have based these forward-looking statements        on        our current expectations, assumptions, estimates and projections. While we        believe these expectations, assumptions, estimates and projections are        reasonable, such forward-looking statements are only predictions and involve        known and unknown risks and uncertainties, many of which are beyond our control.        These and other important factors may cause our actual results, performance        or        achievements to differ materially from any future results, performance or        achievements expressed or implied by these forward-looking        statements.*

**General**

**Results        of Operations**

|                                                                                                                                                                                                                                                                                                                                                                                                                                           |   | **Three                  Months Ended** |   |   | **Six                  Months Ended** |   |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-----------------------------------------|--------|--------|---------------------------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                           |   | **June                  30,**           |   |   | **June                  30,**         |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                           |   | **2007**                                |   |   | **2006**                              |   |   | **2007** |   |   | **2006** |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |                                    |   |   |                                  |   |   |   |   |   |   |   |
| Production                  revenues (in thousands):                                                                                                                                                                                                                                                                                                                                                                                           |   |                                    |   |   |                                  |   |   |   |   |   |   |   |
| Gas                                                                                                                                          |   | $                                       | 1,533  |   |                                  | $      | 2,117 |   |   | $ | 3,316 |   |   | $ | 5,020 |   |
| Oil                                                                                                                                          |   | $                                       | 32     |   |                                  | $      | 20 |   |   | $ | 58 |   |   | $ | 70 |   |
| Total                                                                                                                                        |   | $                                       | 1,565  |   |                                  | $      | 2,137 |   |   | $ | 3,374 |   |   | $ | 5,090 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |                                    |   |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| Production                  volumes:                                                                                                                                                                                                                                                                                                                                                                                                           |   |                                    |   |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| Gas                  (mcf/day)                  (2)                                                                                          |   |                                    | 1,919  |   |                                  |   | 2,630 |   |   |   | 2,106 |   |   |   | 2,816 |   |
| Oil                  (bbls/day)                  (2)                                                                                         |   |                                    | 6      |   |                                  |   | 3 |   |   |   | 6 |   |   |   | 6 |   |
| Total                  (mcfe/day)                  (2)                                                                                       |   |                                    | 1,955  |   |                                  |   | 2,648 |   |   |   | 2,142 |   |   |   | 2,852 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |                                    |   |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| Average                  sales prices:                                                                                                                                                                                                                                                                                                                                                                                                         |   |                                    |   |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| Gas                  (per mcf) (1)                  (2)                                                                                      |   | $                                       | 8.77   |   |                                  | $      | 8.85 |   |   | $ | 8.70 |   |   | $ | 9.85 |   |
| Oil                  (per bbl)                  (2)                                                                                          |   | $                                       | 57.61  |   |                                  | $      | 64.87 |   |   | $ | 57.59 |   |   | $ | 60.45 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |                                    |   |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| Average                  production costs:                                                                                                                                                                                                                                                                                                                                                                                                     |   |                                    |   |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| As                  a percent of                  sales                                                                                      |   |                                    | 30     | %      |                                  |   | 24 | % |   |   | 26 | % |   |   | 19 | % |
| Per                  mcfe                  (2)                                                                                               |   | $                                       | 2.62   |   |                                  | $      | 2.15 |   |   | $ | 2.31 |   |   | $ | 1.85 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                           |   |                                    |   |   |                                  |   |   |   |   |   |   |   |   |   |   |   |
| Depletion                  per                  mcfe                                                                |   | $                                       | 4.73   |   |                                  | $      | 3.50 |   |   | $ | 4.73 |   |   | $ | 3.69 |   |

| (1)   | The                  average sales price per mcf before the effects of hedging was $7.92                  and                  $8.00 for the three months ended June 30, 2007 and 2006, respectively;                  and                  $7.84 and $9.02 for the six months ended June 30, 2007 and 2006,                  respectively. |
|-----------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (2)   | “Mcf”                  means thousand cubic feet, “mcfe” means thousand cubic feet equivalent and                  “bbls” means barrels.  Bbls are converted to mcfe using the                  ratio of six mcfs to one bbl. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

**Natural        Gas Revenues**

**Oil        Revenues**

**Expenses.  **

**Liquidity        and Capital Resources**

**Critical        Accounting Policies**

**Subordination        by Managing General Partner**

**Recently        Issued Financial Accounting Standards**

*Offsetting        of Amounts Related to Certain Contracts,*

*The Fair Value Option for Financial Assets and Financial        Liabilities*

*Fair Value *
*Measurement*

**ITEM        3.  CONTROLS AND PROCEDURES**

**PART        II.                      OTHER        INFORMATION**

**ITEM        6.  Exhibits**

**EXHIBIT        INDEX**

| **Exhibit                  No.** |   | **Description**                                                                                                                                                           |
|----------------------------------|--------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|                             |   |                                                                                                                                                                      |
| 31.1                             |   | Certification                  Pursuant to Rule 13a-14/15(d)-14                                                                                                           |
| 31.2                             |   | Certification                  Pursuant to Rule 13a-14/15(d)-14                                                                                                           |
| 32.1                             |   | Certification                  Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to Section                  906 of                  the Sarbanes-Oxley Act of 2002 |
| 32.2                             |   | Certification                  Pursuant to 18 U.S.C. Section 1350, as Adopted Pursuant to Section                  906 of                  the Sarbanes-Oxley Act of 2002 |

**SIGNATURES**

| Pursuant                  to the requirements of the Securities of the Exchange Act of 1934,                  the                  registrant has duly caused this report to be signed on its behalf                  by the                  undersigned, thereunto duly authorized. |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|                                                                                                                                                                                                                                                                                  |
|                                                                                                                                                                                                                                                                                  |   |   |
|                                                                                                                                                                                                                                                                                  |   |   |
| Atlas                  America Public #12-2003 Limited Partnership                                                                                                                                                                                                                    |
|                                                                                                                                                                                                                                                                                  |   |   |
|                                                                                                                                                                                                                                                                                  |   | Atlas                  Resources, LLC, Managing General Partner |
|                                                                                                                                                                                                                                                                                  |   |   |
| Date:  August                  13, 2007                                                                                                                                                                                                                                     |   | By:/s/                  Freddie M. Kotek |
|                                                                                                                                                                                                                                                                                  |   | Freddie                  M. Kotek, Chairman of the Board of Directors, Chief Executive                  Officer |
|                                                                                                                                                                                                                                                                                  |   | and                  President |
|                                                                                                                                                                                                                                                                                  |   |   |
|                                                                                                                                                                                                                                                                                  |   |   |
| In                  accordance with the Exchange Act, this report has been signed by                  the                  following persons on behalf of the registrant and in the capacities                  and on                  the dates indicated.                          |
|                                                                                                                                                                                                                                                                                  |
|                                                                                                                                                                                                                                                                                  |   |   |
|                                                                                                                                                                                                                                                                                  |   |   |
| Date:  August                  13, 2007                                                                                                                                                                                                                                     |   | By:/s/                  Freddie M. Kotek |
|                                                                                                                                                                                                                                                                                  |   | Freddie                  M. Kotek, Chairman of the Board of Directors, Chief                  Executive |
|                                                                                                                                                                                                                                                                                  |   | Officer                  and President |
|                                                                                                                                                                                                                                                                                  |   |   |
|                                                                                                                                                                                                                                                                                  |   |   |
| Date:  August                  13, 2007                                                                                                                                                                                                                                     |   | By:/s/                  Matthew A. Jones |
|                                                                                                                                                                                                                                                                                  |   | Matthew                  A. Jones, Chief Financial Officer |
|                                                                                                                                                                                                                                                                                  |   |   |
|                                                                                                                                                                                                                                                                                  |   |   |
| Date:  August                  13, 2007                                                                                                                                                                                                                                     |   | By:/s/                  Nancy J. McGurk |
|                                                                                                                                                                                                                                                                                  |   | Nancy                  J. McGurk, Vice President, Chief Accounting Officer |
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