|                                                                                                                                                                                                                                                                                                                                                                                                    | United      States                                                                                  |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------|
|                                                                                                                                                                                                                                                                                                                                                                                                    | Securities      and Exchange Commission                                                             |
|                                                                                                                                                                                                                                                                                                                                                                                                    | Washington,      D.C. 20549                                                                         |
|                                                                                                                                                                                                                                                                                                                                                                                                    | Form      10-K                                                                                      |
| (Mark      One)                                                                                                                                                                                                                                                                                                                                                                                         |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |
| R                                                                                                                                                                                                                                                                                                                                                                                                       | ANNUAL      REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE ACT OF      1934     |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |
| For      the fiscal year ended December 31, 2008                                                                                                                                                                                                                                                                                                                                                        |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |
| o                                                                                                                                                                                                                                                                                                                                                                                                       | TRANSITION      REPORT PURSUANT TO SECTION 13 OR 15 (d) OF THE SECURITIES EXCHANGE ACT OF      1934 |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |
|                                                                                                                                                                                                                                                                                                                                                                                                    | For      the transition period from _____ to _____                                                  |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |
|                                                                                                                                                                                                                                                                                                                                                                                                    | Commission      file number 333-150925-03                                                           |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |
|                                                                                                                                                                                                                                                                                                                                                                                                    | ATLAS      RESOURCES PUBLIC 18-2008 (A) L.P.                                                        |
|                                                                                                                                                                                                                                                                                                                                                                                                    | (Exact      name of registrant as specified in its charter)                                         |
| Delaware                                                                                                                                                                                                                                                                                                                                                                                                |                                                                                                | 26-2202544 |
| (State      or other jurisdiction of                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                | (I.R.S.      Employer |
| Incorporation      or organization)                                                                                                                                                                                                                                                                                                                                                                     |                                                                                                | Identification      No) |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |   |
| Westpointe      Corporate Center One                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |   |
| 1550      Coraopolis Heights Road, 2nd Floor                                                                                                                                                                                                                                                                                                                                                            |                                                                                                |   |
| Moon      Township, PA                                                                                                                                                                                                                                                                                                                                                                                  |                                                                                                | 15108 |
| (Address      of principal executive offices)                                                                                                                                                                                                                                                                                                                                                           |                                                                                                | (Zip      Code) |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |   |
| Registrant’s      telephone number (412)      262-2830                                                                                                                                                                                                                                                                                                                                            |                                                                                                |   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |   |
| Securities      registered under Section 12(b) of the Exchange Act.                                                                                                                                                                                                                                                                                                                                     |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |   |
| Title      of each class                                                                                                                                                                                                                                                                                                                                                                                |                                                                                                | Name      of each exchange on which registered |
| None                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                | None |
|                                                                                                                                                                                                                                                                                                                                                                                                    |                                                                                                |   |
| Securities      registered under Section 12 (g) of the Exchange Act:  Investor      General Partner Units and Limited Partner Units                                                                                                                                                                                                                                                           |
| (Title      of Class)                                                                                                                                                                                                                                                                                                                                                                                   |
|                                                                                                                                                                                                                                                                                                                                                                                                    |
| Indicate      by check mark if the registrant is a well-known seasoned issuer, as      defined in Rule 405 of the Securities      Act.     Yes  ̈ No þ                                                                                                                                                                                                                |
|                                                                                                                                                                                                                                                                                                                                                                                                    |
| Indicate      by check mark if the registrant is not required to file reports pursuant      to Section 13 or Section 15 (d) of the Act. Yes  ̈ No þ                                                                                                                                                                                                                                            |
|                                                                                                                                                                                                                                                                                                                                                                                                    |
| Indicate      by check mark whether the registrant (1) has filed all reports required to      be filed by Section 13 or 15 (d) of the Securities Exchange Act of 1934      during the preceding 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 þ No  ̈ |
|                                                                                                                                                                                                                                                                                                                                                                                                    |
| Indicate      by check mark if disclosure of delinquent filers pursuant to Item 405 of      Regulation S-K is not contained herein, and will not be contained, to the      best of registrant’s knowledge, in definitive proxy or information      statements incorporated by reference in Part III of this Form 10-K or any      amendment to this form 10-K þ                              |
|                                                                                                                                                                                                                                                                                                                                                                                                    |
| Indicate      by check mark whether the registrant is a large accelerated filer, an      accelerated filer, a non-accelerated filer or a smaller reporting company.      See the definitions of “large accelerated filer,” “accelerated filer” and      “smaller reporting company” in Rule 12b-2 of the Exchange Act (Check      one):                             |
|                                                                                                                                                                                                                                                                                                                                                                                                    |
| Large      accelerated filer  ̈  Accelerated      filer  ̈  Non-accelerated      filer  ̈  Smaller      reporting company þ                                                                                                                                                                                                                              |
|                                                                                                                                                                                                                                                                                                                                                                                                    |
| Indicate      by check mark whether the registrant is a shell company (as defined in      Rule 12b-2 of the Act). Yes  ̈ No þ                                                                                                                                                                                                                                                                  |
|                                                                                                                                                                                                                                                                                                                                                                                                    |
| DOCUMENTS      INCORPORATED BYREFERENCE:  None                                                                                                                                                                                                                                                                                                                                                |

| PART      I   |   |                                                                                              | PAGE   |
|---------------|--------|---------------------------------------------------------------------------------------------------|--------|
|          |   |                                                                                              |   |
| Item      1:  |   | Description      of Business                                                                      | 3-5    |
|          |   |                                                                                              |   |
| Item      2:  |   | Description      of Properties                                                                    | 5-9    |
|          |   |                                                                                              |   |
| Item      3:  |   | Legal      Proceedings                                                                            | 9      |
|          |   |                                                                                              |   |
| Item      4:  |   | Submission      of Matters to a Vote of Security Holders                                          | 9      |
|          |   |                                                                                              |   |
| PART      II  |   |                                                                                              |   |
|          |   |                                                                                              |   |
| Item      5:  |   | Market      for Registrant’s Common Equity and Related Security Holder      Matters         | 9-10   |
|          |   |                                                                                              |   |
| Item      7:  |   | Management’s      Discussion and Analysis of Financial Condition or Plan of      Operations | 10-14  |
|          |   |                                                                                              |   |
| Item      8:  |   | Financial      Statements                                                                         | 15-28  |
|          |   |                                                                                              |   |
| Item      9:  |   | Changes      in and Disagreements with Accountants on Accounting and Financial      Disclosure    | 28     |
|          |   |                                                                                              |   |
| Item      9A: |   | Controls      and Procedures                                                                      | 28-29  |
|          |   |                                                                                              |   |
| Item      9B: |   | Other      Information                                                                            | 29     |
|          |   |                                                                                              |   |
| PART      III |   |                                                                                              |   |
|          |   |                                                                                              |   |
| Item      10: |   | Directors,      Executive Officers and Corporate Governance                                       | 29-31  |
|          |   |                                                                                              |   |
| Item      11: |   | Executive      Compensation                                                                       | 32     |
|          |   |                                                                                              |   |
| Item      12: |   | Security      Ownership of Certain Beneficial Owners and Management                               | 32     |
|          |   |                                                                                              |   |
| Item      13: |   | Certain      Relationships and Related Transactions, and Director      Independence               | 32-33  |
|          |   |                                                                                              |   |
| Item      14: |   | Principal      Accountant Fees and Services                                                       | 33     |
|          |   |                                                                                              |   |
| PART      IV  |   |                                                                                              |   |
|          |   |                                                                                              |   |
| Item      15: |   | Exhibits                                                                                          | 34     |
|          |   |                                                                                              |   |
|          |   |                                                                                              |   |
| SIGNATURES    | 35     |

| ·   | new      well permit and well registration requirements, procedures and      fees; |
|--------------------|------------------------------------------------------------------------------------|

| ·   | minimum      well spacing requirements; |
|--------------------|-----------------------------------------|

| ·   | restriction      on well locations and underground gasstorage; |
|--------------------|----------------------------------------------------------------|

| ·   | certain      well site restoration, groundwater protection and safety      measures; |
|--------------------|--------------------------------------------------------------------------------------|

| ·   | landowner      notification requirements; |
|--------------------|-------------------------------------------|

| ·   | certain      bonding or other security measures; |
|--------------------|--------------------------------------------------|

| ·   | various      reporting requirements; |
|--------------------|--------------------------------------|

| ·   | well      plugging standards and procedures;and |
|--------------------|-------------------------------------------------|

| ·   | broad      enforcement powers. |
|--------------------|--------------------------------|

|                           |   | Development      Wells |   |
|--------------------------------|--------|------------------------|--------|
| Period      Ended December 31, |   | Productive      (1)    |   |   | Dry      (2) |   |
|                           |   | Gross      (3)         |   |   | Net      (4) |   |   | Gross      (3) |   |   | Net      (4) |   |
| 2008                           |   |                   | 129    |   |   |   | 113.05 |   |   |   | — |   |   |   | — |   |

| (1)   | A      “productive well” generally means a well that is not a dry      hole. |
|-----------------|------------------------------------------------------------------------------------------|

| (2)   | A      “dry hole” generally means a well found to be incapable of producing      either oil or gas in sufficient quantities to justify completion as an oil      or gas well. The term “completion” refers either to the installation of      permanent equipment for the production of oil or gas or, in the case of a      dry hole, to the reporting of the abandonment of the well to the      appropriate regulatory agency. |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (3)   | A      “gross” well is a well in which we have a working  interest. |
|-----------------|---------------------------------------------------------------------------------|

| (4)   | A      “net” well equals the actual working interest we own in one gross well      divided by one hundred. For example, a 50% working interest in a well is      one gross well, but a .50 net well. |
|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   | Number      of Producing Wells |   |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|--------------------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   | Gross                          |   |   | Net |   |
| Gas                                                                                                      |   |                           | 4      |   |   |   | 3.50 |   |

|              |   |                |    |   |                     |   |   | Average             |   |
|-------------------|--------|---------------------|---------|--------|--------------------------|--------|--------|---------------------|--------|
| Period            |   |                |    |   |                     |   |   |                |   |   |   |   |   | Production      Cost |   |
| Ended             |   | Production          |    |   | Average      Sales Price |   |   | (Lifting      Cost) |   |
| December      31, |   | Oil      (bbls) (1) |    |   | Gas      (mcf) (1)       |   |   | per      bbl (1)    |   |   | per      mcf (1) |   |   | per      mcfe (1)      (2) |   |
| 2008              |   |                | — |   |                     |   | 12,200 |                |   | $ | — |   |   | $ | 7.59 |   |   | $ | 1.15 |   |

| (1)   | “Mcf”      means one thousand cubic feet of natural gas.  “Mcfe” means a      thousand cubic feet equivalent.  Oil production is converted to      mcfe at the rate of six mcf per barrel(“bbl”). |
|-----------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (2)   | Lifting      costs include labor to operate the wells and related equipment, repairs      and maintenance, materials and supplies, property taxes, insurance and      gathering charges. |
|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |   | December      31, |   |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |   | 2008              |   |
| Natural      gas (per      mcf)                                                                                      |   | $                 | 5.82   |   |
| Oil      ( per      bbl)                                                                                             |   |              | 33.76  |   |

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |   | At      December 31, |       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|----------------------|------------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |   | 2008                 |       |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |   |                 |       |
| Natural      gas reserves – Proved Reserves (Mcf) (1)(4):                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   |                 |       |
| Proved      developed reserves      (2)                                                                                                                                                                           |   |                 | 15,555,900 |   |
| Total      proved reserves of natural      gas                                                                                                                                                                                        |   |                 | 15,555,900 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |   |                 |       |   |
| Oil      reserves – Proved Reserves (Bbl) (1)(4):                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |                 |       |   |
| Proved      developed reserves      (2)                                                                                                                                                                           |   |                 | 2,600      |   |
| Total      proved reserves of      oil                                                                                                                                                                                                |   |                 | 2,600      |   |
| Total      proved reserves      (Mcfe)                                                                                                                                         |   |                 | 15,571,500 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |   |                 |       |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |   |                 |       |   |
| PV-10      estimate of cash flows of proved reserves (3)(4):                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |   |                 |       |   |
| Proved      developed      reserves                                                                                                                                                                               |   | $                    | 14,621,900 |   |
| Total      PV-10      estimate                                                                                                                                                                                                        |   | $                    | 14,621,900 |   |
| PV-10      estimate per investor partner unit      (5)                                                                                                                         |   | $                    | 500        |   |
| Undiscounted      estimate per investor partner unit      (5)                                                                                                                  |   | $                    | 1,300      |   |

| (1)   | “Proved      reserves” generally means the estimated quantities of crude oil, natural      gas, and natural gas liquids which geological and engineering data      demonstrate with reasonable certainty to be recoverable in future years      from known reservoirs under existing economic and operating conditions,      i.e., prices and costs as of the date the estimate is made. Prices include      consideration of changes in existing prices provided only by contractual      arrangements, but not on escalations based upon future conditions.      Reservoirs are considered proved if economic production is supported by      either actual production or conclusive formation test. The area of a      reservoir considered proved includes that portion delineated by drilling      and defined by gas-oil and/or oil-water contacts, if any, and the      immediately adjoining portions not yet drilled, but which can be      reasonably judged as economically productive on the basis of available      geological and engineering data. |
|-----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (2)   | “Proved      developed reserves” generally means reserves that can be expected to be      recovered through existing wells with existing equipment and operating      methods. |
|-----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (3)   | The      present value of estimated future net cash flows is calculated by      discounting estimated future net cash flows by 10%    annually. |
|-----------------|-------------------------------------------------------------------------------------------------------------------------------------------------|

| (4)   | Please      see Regulation S-X rule 4-10 for complete definitions of each reserve      category. |
|-----------------|--------------------------------------------------------------------------------------------------|

| (5)   | This      value per $10,000 unit is determined by following the methodology used for      determining our proved reserves using the data discussed      above.  However, this value does not necessarily reflect the      fair market value of a unit, and each unit is illiquid.  Also,      the value of a unit for purposes of presentment of the unit to our MGP for      purchase is different because it is calculated under a formula set forth      in the partnership agreement. |
|-----------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|                                                                                                                                                                                                                                                                                                                                                                                       |   | Developed      Acreage |     |   | Undeveloped      Acreage (3) |   |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|------------------------|----------|--------|------------------------------|--------|
| Location                                                                                                                                                                                                                                                                                                                                                                                   |   | Gross      (1)         |     |   | Net      (2)                 |   |   | Gross      (1) |   |   | Net      (2) |   |
| Indiana                                                                        |   |                   | 1,440.00 |   |                         |   | 1,202.68 |   |   |   | 160.00 |   |   |   | 121.60 |   |
| Michigan                                                                       |   |                   | 880.00   |   |                         |   | 781.00 |   |   |   | 680.00 |   |   |   | 632.00 |   |
| Ohio                                                                           |   |                   | 12.27    |   |                         |   | 1.78 |   |   |   | — |   |   |   | — |   |
| Pennsylvania                                                                   |   |                   | 2,293.07 |   |                         |   | 1,987.67 |   |   |   | 1,010.49 |   |   |   | 893.79 |   |
| Tennessee                                                                      |   |                   | 861.34   |   |                         |   | 826.74 |   |   |   | — |   |   |   | — |   |
| West      Virginia                                                             |   |                   | 68.30    |   |                         |   | 51.23 |   |   |   | 90.24 |   |   |   | 60.15 |   |
| Total                                                                                                        |   |                   | 5,554.98 |   |                         |   | 4,851.10 |   |   |   | 1,940.73 |   |   |   | 1,707.54 |   |

| (1)   | A      “gross” acre is an acre in which we own a working  interest. |
|-----------------|---------------------------------------------------------------------------------|

| (2)   | A      “net” acre equals the actual working interest we own in one gross acre      divided by one hundred. For example, a 50% working interest in an acre is      one gross acre, but a 0.5 net acre. |
|-----------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (3)   | “Undeveloped      acreage” means those lease acres on which wells have not been drilled or      completed to a point that would permit the production of commercial      quantities of oil and gas regardless of whether or not the acreage      contains proved reserves. |
|-----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | our      MGP consent; |
|--------------------|-----------------------|

| ·   | the      transfer not result in materially adverse tax consequences to us;      and |
|--------------------|-------------------------------------------------------------------------------------|

| ·   | the      transfer not violate federal or state securities  laws. |
|--------------------|------------------------------------------------------------------|

| ·   | the      assignor gives the assignee theright; |
|--------------------|------------------------------------------------|

| ·   | our      MGP consents to the substitution; |
|--------------------|--------------------------------------------|

| ·   | the      assignee pays to us all costs and expenses incurred in connection with the      substitution; and |
|--------------------|------------------------------------------------------------------------------------------------------------|

| ·   | the      assignee executes and delivers the instruments, which our MGP requires to      effect the substitution and to confirm his or her agreement to be bound by      the terms of our partnershipagreement. |
|--------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |   | Period      April 8, 2008 |    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|---------------------------|---------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |   | (date      of formation)  |    |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |   | Through                   |    |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |   | December      31,         |    |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |   | 2008                      |    |
| Production      revenues (in thousands):                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   |                      |    |
| Gas                                                                                                                                |   | $                         | 92,800  |   |
| Oil                                                                                                                                |   | $                         | — |   |
| Total                                                                                                                              |   | $                         | 92,800  |   |
| Production      volumes:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   |                      |    |   |
| Gas      (mcf/day) (1)                                                                                                             |   |                      | 719     |   |
| Oil      (bbls/day) (1)                                                                                                            |   |                      | — |   |
| Total      (mcfe/day) (1)                                                                                                          |   |                      | 719     |   |
| Average      sales price:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |   |                      |    |   |
| Gas      (per mcf) (1)                                                                                                             |   | $                         | 7.59    |   |
| Oil      (per bbl) (1)                                                                                                             |   | $                         | — |   |
| Average      production costs:                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |   |                      |    |   |
| As      a percent of      revenues                                                                                                 |   |                      | 15      | % |
| Per      mcfe (1)                                                                                                                  |   | $                         | 1.15    |   |
| Depletion      per      mcfe                                                                              |   | $                         | 8.70    |   |

| (1)   | “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. |
|-----------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|                                         |   | 2008   |        |
|----------------------------------------------|--------|--------|-------------|
| ASSETS                                       |   |   |        |
| Current      assets:                         |   |   |        |
| Cash      and cash equivalents               |   | $      | 20,839,700  |   |
| Accounts      receivable-affiliate           |   |   | 70,600      |   |
| Total      current assets                    |   |   | 20,910,300  |   |
|                                         |   |   |        |   |
| Oil      and gas properties, net             |   |   | 47,592,400  |   |
| Construction      in progress                |   |   | 115,371,700 |   |
|                                         |   | $      | 183,874,400 |   |
|                                         |   |   |        |   |
|                                         |   |   |        |   |
| LIABILITIES      AND PARTNERS’ CAPITAL |   |   |        |   |
| Current      liabilities:                    |   |   |        |   |
| Accrued      liabilities                     |   | $      | 3,900       |   |
|                                         |   |   |        |   |
| Asset      retirement obligations            |   |   | 957,000     |   |
|                                         |   |   |        |   |
| Partners’      capital:                |   |   |        |   |
| Managing      general partner                |   |   | 6,395,600   |   |
| Investor      partners (20,152.50 units)     |   |   | 201,171,100 |   |
| Investor      subscriptions receivable       |   |   | (24,653,200 | ) |
| Total      partners' capital                 |   |   | 182,913,500 |   |
|                                         |   | $      | 183,874,400 |   |

| REVENUES                                      |   |   |    |
|-----------------------------------------------|--------|--------|---------|
| Natural      gas and oil                      |   | $      | 92,800  |   |
| Total      revenues                           |   |   | 92,800  |   |
|                                          |   |   |    |   |
| COST      AND EXPENSES                        |   |   |    |   |
| Production                                    |   |   | 14,100  |   |
| Depletion                                     |   |   | 106,300 |   |
| Accretion      of asset retirement obligation |   |   | 39,000  |   |
| General      and administrative               |   |   | 12,000  |   |
| Total      expenses                           |   |   | 171,400 |   |
| Net      loss                                 |   | $      | (78,600 | ) |
|                                          |   |   |    |   |
| Allocation      of net loss:                  |   |   |    |   |
| Managing      general partner                 |   | $      | (6,900  | ) |
| Investor      partners                        |   | $      | (71,700 | ) |
| Net      loss per investor partnership unit   |   | $      | (4      | ) |

|                                                                |   |     |        |   |     |   |        |         |   |   |        |   |
|---------------------------------------------------------------------|--------|----------|-------------|--------|----------|--------|-------------|--------------|--------|--------|-------------|--------|
|                                                                |   | Managing |        |   |     |   |        | Investor     |   |   |        |   |
|                                                                |   | General  |        |   | Investor |   |        | Subscription |   |   |        |   |
|                                                                |   | Partner  |        |   | Partners |   |        | Receivable   |   |   | Total       |   |
|                                                                |   |     |        |   |     |   |        |         |   |   |        |   |
| Balance      at April 8, 2008                                       |   | $        | —     |   |     | $      | —     |         |   | $      | —     |   |   | $ | — |   |
|                                                                |   |     |        |   |     |   |        |         |   |   |        |   |   |   |   |   |
| Partners’      capital contributions:                         |   |     |        |   |     |   |        |         |   |   |        |   |   |   |   |   |
| Cash                                                                |   |     | 100         |   |     |   | 201,242,800 |         |   |   | (24,653,200 | )      |   |   | 176,589,700 |   |
| Syndication      and offering costs                                 |   |     | 10,119,500  |   |     |   | —     |         |   |   | —     |   |   |   | 10,119,500 |   |
| Tangible      equipment/leasehold costs                             |   |     | 6,402,400   |   |     |   | —     |         |   |   | —     |   |   |   | 6,402,400 |   |
| Total      contributions                                            |   |     | 16,522,000  |   |     |   | 201,242,800 |         |   |   | (24,653,200 | )      |   |   | 193,111,600 |   |
|                                                                |   |     |        |   |     |   |        |         |   |   |        |   |   |   |   |   |
| Syndication      and offering costs, immediately charged to capital |   |     | (10,119,500 | )      |     |   | —     |         |   |   | —     |   |   |   | (10,119,500 | ) |
|                                                                |   |     | 6,402,500   |   |     |   | 201,242,800 |         |   |   | (24,653,200 | )      |   |   | 182,992,100 |   |
|                                                                |   |     |        |   |     |   |        |         |   |   |        |   |   |   |   |   |
| Participation      in revenue and expenses:                         |   |     |        |   |     |   |        |         |   |   |        |   |   |   |   |   |
| Net      production revenues                                        |   |     | 23,200      |   |     |   | 55,500      |         |   |   | —     |   |   |   | 78,700 |   |
| Depletion                                                           |   |     | (15,100     | )      |     |   | (91,200     | )            |   |   | —     |   |   |   | (106,300 | ) |
| Accretion      of asset retirement obligations                      |   |     | (11,500     | )      |     |   | (27,500     | )            |   |   | —     |   |   |   | (39,000 | ) |
| General      and administrative                                     |   |     | (3,500      | )      |     |   | (8,500      | )            |   |   | —     |   |   |   | (12,000 | ) |
| Net      loss                                                       |   |     | (6,900      | )      |     |   | (71,700     | )            |   |   | —     |   |   |   | (78,600 | ) |
|                                                                |   |     |        |   |     |   |        |         |   |   |        |   |   |   |   |   |
| Balance      at December 31, 2008                                   |   | $        | 6,395,600   |   |     | $      | 201,171,100 |         |   | $      | (24,653,200 | )      |   | $ | 182,913,500 |   |

|                                                                                      |   | 2008   |         |
|-------------------------------------------------------------------------------------------|--------|--------|--------------|
| Cash      flows from operating activities:                                                |   |   |         |
| Net      loss                                                                             |   | $      | (78,600      | ) |
| Adjustments      to reconcile net loss to net cash provided by operating      activities: |   |   |         |   |
| Depletion                                                                                 |   |   | 106,300      |   |
| Accretion      of asset retirement obligation                                             |   |   | 39,000       |   |
| Decrease      in accounts receivable-affiliate                                            |   |   | (70,600      | ) |
| Decrease      in accrued liabilities                                                      |   |   | 3,900        |   |
| Net      cash provided by operating activities                                            |   |   | —      |   |
|                                                                                      |   |   |         |   |
| Cash      flows from investing activities:                                                |   |   |         |   |
| Oil      and gas well drilling contracts paid to MGP                                      |   |   | (155,750,000 | ) |
| Net      cash used in investing activities                                                |   |   | (155,750,000 | ) |
|                                                                                      |   |   |         |   |
| Cash      flows from financing activities:                                                |   |   |         |   |
| Initial      capital contribution by MGP                                                  |   |   | 100          |   |
| Partners’      capital contributions                                                |   |   | 176,589,600  |   |
| Net      cash provided by financing activities                                            |   |   | 176,589,700  |   |
|                                                                                      |   |   |         |   |
| Net      increase in cash and cash equivalents                                            |   |   | 20,839,700   |   |
| Cash      and cash equivalents at beginning of period                                     |   |   | —      |   |
| Cash      and cash equivalents at end of period                                           |   | $      | 20,839,700   |   |
|                                                                                      |   |   |         |   |
| Supplemental Schedule      of non-cash investing and financing activities:                |   |   |         |   |
|                                                                                      |   |   |         |   |
|                                                                                      |   |   |         |   |
| Assets      contributed by the managing general partner:                                  |   |   |         |   |
| Tangible      equipment                                                                   |   | $      | 4,920,700    |   |
| Lease      costs                                                                          |   |   | 1,481,700    |   |
| Syndication      and offering costs                                                       |   |   | 10,119,500   |   |
|                                                                                      |   | $      | 16,521,900   |   |
|                                                                                      |   |   |         |   |
| Asset      retirement obligation                                                          |   | $      | 918,000      |   |

| Oil      and gas properties consist of the following at the date      indicated:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |   | December      31, |       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-------------------|------------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |   | 2008              |       |
| Natural      gas and oil properties:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |   |              |       |
| Proved      properties:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   |              |       |
| Leasehold      interest                                                                                                                  |   | $                 | 1,481,700  |   |
| Wells      and related      equipment                                                                                                    |   |              | 46,217,000 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |   |              | 47,698,700 |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |   |              |       |   |
| Accumulated      depletion                                                                                                               |   |              | (106,300   | ) |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                    |   | $                 | 47,592,400 |   |

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   | Managing |   |   |              |   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|----------|--------|--------|-------------------|--------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   | General  |   |   | Other             |   |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |   | Partner  |   |   | Partners      (3) |   |
| Organization      and offering      costs                                                                                                             |   |     | 100    | %      |              |   | 0 | % |
| Lease      costs                                                                                                                                      |   |     | 100    | %      |              |   | 0 | % |
| Revenues      (1)                                                                                                                                     |   |     | 29.50  | %      |              |   | 70.50 | % |
| Operating      costs, administrative costs, direct costs and all other operating costs      (2)                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |   |     | 29.50  | %      |              |   | 70.50 | % |
| Intangible      drilling      costs                                                                                                                   |   |     | 0      | %      |              |   | 100 | % |
| Tangible      equipment      costs                                                                                                                    |   |     | 40     | %      |              |   | 60 | % |

| (1)   | Subject      to the MGP’s subordination obligation, substantially all partnership      revenues will be shared in the same percentage as capital contributions      are to the total partnership capital contributions, except that the MGP      will receive an additional 10% of the partnership  revenues. |
|-----------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| (2)   | These      costs will be charged to the partners in the same ratio as the related      production revenues are credited. |
|-----------------|--------------------------------------------------------------------------------------------------------------------------|

| (3)   | Other      Partners include both investor limited partners and investor general      partners.  General Partner units can be converted limited      partner units when all wells have been drilled and completed. Thereafter,      the investor general partner will have limited liability as a limited      partner under the Delaware Revised Uniform Limited Partnership Act with      respect to his or her interest in the  partnership. |
|-----------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Drilling      contracts to      drill and complete wells for the Partnership are charged at cost plus 18%.      The cost of the wells includes reimbursement to the Partnership's MGP of      its general and administrative overhead cost ($60,000 per well for      Marcellus wells and $15,000 per well for all other wells). Subscriptions      totaling $24,653,200 were received by the Partnership’s broker/dealer and      held on account at December 31, 2008. These funds were subsequently      received by the Partnership in January 2009. The Partnership paid      $176,589,600 to its MGP in 2008 under the drilling contract, of which      $85,871,100 was used for drilling costs and the remaining balance of      $115,371,700 is shown as part of construction in progress on the      Partnership’s Balance Sheet. |
|--------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | The      Partnership's MGP contributed undeveloped leases necessary to cover each      of the Partnership’s prospects and as of December 31, 2008 received a      credit to its capital account in the Partnership of      $1,481,700. |
|--------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | The      Partnership’s MGP has contributed $4,920,700 in tangible equipment cost as      of December 31, 2008. |
|--------------------|----------------------------------------------------------------------------------------------------------------------|

| ·   | Administrative      costs which are included in general and administrative expenses in the      Partnership’s Statement of Operations are payable at $75 per well per      month. Administrative costs incurred in 2008 were  $100. |
|--------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Monthly      well supervision fees which are included in production expenses in the      Partnerships Statement of Operations are payable at $975 per well per      month for Marcellus wells and $1,500, for New Albany and Indiana wells.      For all other wells a fee of $392 is charged per well per month for      operating and maintaining the wells. Well supervision fees incurred in      2008 were $800. |
|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Transportation      fees which are included in production expenses in the Partnerships      Statement of Operations are generally payable at 13% of the natural gas      sales price. Transportation fees incurred in 2008 were      $12,700. |
|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Direct      costs which are included in production and general administrative expenses      in the Partnership’s Statements of Operations are payable to the MGP and      its affiliates as reimbursement for all costs expended on the      Partnership’s behalf. Direct costs incurred in 2008 were      $12,500. |
|--------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | Assets      contributed from the MGP which are disclosed on the Partnership's      Statement of Cash Flows as non-cash investing and financing activities for      the period ended December 31, 2008 were  $16,521,900. |
|--------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | The      MGP received a credit to its capital account of $10,119,500 in 2008 for      fees, commissions and reimbursement costs to organize the      Partnership. |
|--------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------|

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   | Period      Ended |    |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|-------------------|---------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   | December      31, |    |
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                     |   | 2008              |    |
| Asset      retirement obligation at beginning of period                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |   | $                 | — |   |
| Liabilities      incurred from drilling      wells                                                                                        |   |              | 918,000 |   |
| Accretion      expense                                                                                                                    |   |              | 39,000  |   |
| Asset      retirement obligation at end of      period                                                                                    |   | $                 | 957,000 |   |

| (1)   | Capitalized      Costs Related to Oil and Gas Producing  Activities |
|-----------------|---------------------------------------------------------------------|

|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |   | At      December 31, |       |
|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|----------------------|------------|
|                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |   | 2008                 |       |
| Mineral      interest in proved properties:                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 |   | $                    | 1,481,700  |   |
| Wells      and related      equipment                                                                                          |   |                 | 46,217,000 |   |
| Accumulated      depletion                                                                                                     |   |                 | (106,300   | ) |
| Net      capitalized      cost                                                                                                                                                             |   | $                    | 47,592,400 |   |

| (2)   | Oil      and Gas Reserve Information |
|-----------------|--------------------------------------|

|                                                                                                                                                                                                                                                                                                        |   | Natural      Gas |       |   | Oil    |   |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|--------|------------------|------------|--------|--------|--------|
|                                                                                                                                                                                                                                                                                                        |   | (Mcf)            |       |   | (Bbls) |   |
| Proved      developed reserves:                                                                                                                                                                                                                                                                             |   |             |       |   |   |   |
| Beginning      of      period                                              |   |             | —    |   |   |   | — |   |
| Proved      developed reserves                                                                                                                                                                                                                                                                              |   |             | 15,568,100 |   |   |   | 2,600 |   |
| Production                                                                 |   |             | (12,200    | )      |   |   | — |   |
|                                                                                                                                                                                                                                                                                                        |   |             |       |   |   |   |   |   |
| Balance      December 31, 2008                                                                                                                                                                                                                                                                              |   |             | 15,555,900 |   |   |   | 2,600 |   |

| NAME                    | AGE    | POSITION OR      OFFICE                                                             |
|-------------------------|--------|-------------------------------------------------------------------------------------|
|                    |   |                                                                                |
| Freddie      M. Kotek   | 53     | Chairman      of the Board of Directors, Chief Executive Officer and      President |
| Frank      P. Carolas   | 49     | Executive      Vice President – Land and Geology and a Director               |
| Jeffrey      C. Simmons | 50     | Executive      Vice President – Operations and a Director                     |
| Jack      L. Hollander  | 52     | Senior      Vice President – Direct Participation Programs                    |
| Sean      P. McGrath    | 37     | Chief      Accounting Officer                                                       |
| Michael      L. Staines | 59     | Senior      Vice President, Secretary and a Director                                |
| Matthew      A. Jones   | 47     | Chief      Financial Officer                                                        |

| ·   | the      approximate amount of an individual’s professional time devoted to the      business and affairs of our MGP and Atlas America have been aggregated      because there is no reasonable method for them to distinguish their      activities between the two companies;and |
|--------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ·   | for      those individuals who also hold senior positions with other affiliates of      our MGP, if it is stated that they devote approximately 100% of their      professional time to our MGP and Atlas America, it is because either the      other affiliates are not currently active in drilling new wells, such as      Viking Resources or Resource Energy, and the individuals are not required      to devote a material amount of their professional time to the affiliates,      or there is no reasonable method to distinguish their activities between      our MGP and Atlas America as compared with the other affiliates of our      MGP, such as Viking Resources or Resource  Energy. |
|--------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| ITEM      13. | CERTAIN      RELATIONSHIPS AND RELATED TRANSACTIONS, AND DIRECTOR INDEPENDENCE |
|---------------|-------------------------------------------------------------------------------------|

|   | Description                                                     | Location                                 |
|--------|-----------------------------------------------------------------|------------------------------------------|
|   |                                                            |                                     |
| 4(a)   | Certificate      of Limited Partnership for Atlas Resources     | Previously      filed in our Form S-1 on |
|   | Public      18-2008 (A) L.P.                                    | October      15, 2008                    |
|   |                                                            |                                     |
| 4(b)   | Amended      and Restated Certificate and Agreement of Limited  | Previously      filed in our Form S-1 on |
|   | Partnership      for Atlas Resources Public 18-2008 (A) L.P.(1) | October      15, 2008                    |
|   |                                                            |                                     |
| 4(c)   | Drilling      and Operating Agreement for Atlas                 | Previously      filed in our Form S-1 on |
|   | Resources      Public 18-2008 (A) L.P.(1)                       | October      15, 2008                    |
|   |                                                            |                                     |
| 31.1   | Rule      13a-14(a)/15(d) – 14 (a) Certification          |                                     |
|   |                                                            |                                     |
| 31.2   | Rule      13a-14(a)/15(d) – 14 (a) Certification.         |                                     |
|   |                                                            |                                     |
| 32.1   | Section      1350 Certification.                                |                                     |
|   |                                                            |                                     |
| 32.2   | Section      1350 Certification.                                |                                     |

| (1) | Filed      on October 15, 2008 in the Form S-1A Registration Statement dated October      15, 2008, File No. 333-150925-03 |
|-----|----------------------------------------------------------------------------------------------------------------------------|

| In      accordance with Section 13 or 15(d) of the Exchange Act, the registrant      caused this report to be signed on its |
|-----------------------------------------------------------------------------------------------------------------------------|
| behalf      by the undersigned, thereunto duly authorized.                                                                  |
|                                                                                                                        |
|                                                                                                                        |
| Atlas      Resources Public 18-2008 (A) L.P.                                                                                |
|                                                                                                                        |   |   |
| Date:  March      30, 2009                                                                                        |   | Atlas      Resources, LLC, Managing General Partner |
|                                                                                                                        |   |   |
|                                                                                                                        |   | 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:  March      30, 2009                                                                                        |   | By: /s/ Freddie M.      Kotek |
|                                                                                                                        |   | Freddie      M. Kotek, Chairman of the Board of Directors, Chief    Executive |
|                                                                                                                        |   | Officer      and President |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |
| Date:  March      30, 2009                                                                                        |   | By: /s/ Frank P.      Carolas |
|                                                                                                                        |   | Frank      P. Carolas, Executive Vice President – Land and Geology |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |
| Date:  March      30, 2009                                                                                        |   | By: /s/ Jeffrey C.      Simmons |
|                                                                                                                        |   | Jeffrey      C. Simmons, Executive Vice President – Operations |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |
| Date:  March      30, 2009                                                                                        |   | By: /s/ Sean P.      McGrath |
|                                                                                                                        |   | Sean      P. McGrath, Chief Accounting Officer |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |
| Date:  March      30, 2009                                                                                        |   | By: /s/ Matthew A.      Jones |
|                                                                                                                        |   | Matthew      A. Jones, Chief Financial Officer |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |
|                                                                                                                        |   |   |