|                          |
|--------------------------|
|                          |  |
| Nevada                   | 95-2636730 |
| (State of Incorporation) | (I.R.S. Employer Identification No.) |

|                                         |
|-----------------------------------------|
|                                         |  |  |
| Title of Each Class                     |   | Name of Each Exchange on Which Registered |
| Common Stock, par value $0.01 per share |   | NASDAQ Global Select Market |

----

|                                                                                      |
|--------------------------------------------------------------------------------------|
|                                                                                      |  |
| Large accelerated filer  £                                            | Accelerated filer  x |
| Non-accelerated filer  £(Do not check if a smaller reporting company) | Smaller reporting company  o |

----

----

|        |
|--------|
|        |  |  |  |
| (a)    | (3 | ) | Exhibits: |
|   |   | See Exhibits Index. |

|                                                                                                                                                                                                      |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
|                                                                                                                                                                                                      |  |  |  |  |  |  |  |  |  |  |  |  |
|                                                                                                                                                                                                 |   |   |   | Incorporated by Reference |   |   |
| ExhibitNumber                                                                                                                                                                                        |    | Exhibit Description |   | Form |    | SEC FileNumber |    | Exhibit |   | Filing Date |    | FiledHerewith |
|                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |   |   |   |   |
| 10.21 †                                                                                                                                                                                        |   | Domestic Crude Oil Purchase Agreement between Suncor Energy Marketing, Inc. and PDC, dated May 18, 2009. |   | 10-K/A |   | 000-07246 |   | 10.21 |   | 4/21/2011 |   |   |
|                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |   |   |   |   |
| 10.22 †                                                                                                                                                                                        |   | Gas Purchase Agreement between Williams Production RMT Company, Riley Natural Gas and Petroleum Development Corporation, dated as of March 31, 2009. |   | 10-K/A |   | 000-07246 |   | 10.22 |   | 4/21/2011 |   |   |
|                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |   |   |   |   |
| 10.23 †                                                                                                                                                                                        |   | Gas Purchase and Processing Agreement between Duke Energy Field Services, Inc.; United States Exploration, Inc.; and Petroleum Development Corporation, dated as of October 28, 1999. |   | 10-K/A |   | 000-07246 |   | 10.23 |   | 4/21/2011 |   |   |
|                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |   |   |   |   |
| 31.1                                                                                                                                                                                                 |   | Certification by Chief Executive Officer pursuant to Rule 13a-14(a) and 15d-14(a) of the Exchange Act Rules, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |   |   |   |   |   |   |   |   |   | X |
|                                                                                                                                                                                                 |   |   |   |   |   |   |   |   |   |   |   |   |
| 31.2                                                                                                                                                                                                 |   | Certification by Chief Financial Officer pursuant to Rule 13a-14(a) and 15d-14(a) of the Exchange Act Rules, as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |   |   |   |   |   |   |   |   |   | X |
| † Confidential portions of this document have been omitted and filed separately with the SEC pursuant to Exchange Act Rule 24b-2.  The confidential treatment request is pending SEC approval. |

----

|        |
|--------|
|        |  |
|   | PETROLEUM DEVELOPMENT CORPORATION |
|   |   |
|   | By /s/ Richard W. McCullough |
|   | Richard W. McCullough, |
|   | Chairman and Chief Executive Officer |
|   |   |
|   | May 18, 2011 |

|                           |
|---------------------------|
|                           |  |  |  |  |
| Signature                 |   | Title |   | Date |
|                      |   |   |   |   |
| /s/ Richard W. McCullough |   | Chairman and Chief Executive Officer |   | May 18, 2011 |
| Richard W. McCullough     |   | (principal executive officer) |   |   |
|                      |   |   |   |   |
| /s/ Gysle R. Shellum      |   | Chief Financial Officer |   | May 18, 2011 |
| Gysle R. Shellum          |   | (principal financial officer) |   |   |
|                      |   |   |   |   |
| /s/ R. Scott Meyers       |   | Chief Accounting Officer |   | May 18, 2011 |
| R. Scott Meyers           |   | (principal accounting officer) |   |   |
|                      |   |   |   |   |
| /s/ Daniel W. Amidon      |   | General Counsel and Corporate Secretary |   | May 18, 2011 |
| Daniel W. Amidon          |   |   |   |   |
|                      |   |   |   |   |
| /s/ Joseph E. Casabona    |   | Director |   | May 18, 2011 |
| Joseph E. Casabona        |   |   |   |   |
|                      |   |   |   |   |
| /s/ Anthony J. Crisafio   |   | Director |   | May 18, 2011 |
| Anthony J. Crisafio       |   |   |   |   |
|                      |   |   |   |   |
| /s/ Larry F. Mazza        |   | Director |   | May 18, 2011 |
| Larry F. Mazza            |   |   |   |   |
|                      |   |   |   |   |
| /s/ David C. Parke        |   | Director |   | May 18, 2011 |
| David C. Parke            |   |   |   |   |
|                      |   |   |   |   |
| /s/ Jeffrey C. Swoveland  |   | Director |   | May 18, 2011 |
| Jeffrey C. Swoveland      |   |   |   |   |
|                      |   |   |   |   |
| /s/ James M. Trimble      |   | Director |   | May 18, 2011 |
| James M. Trimble          |   |   |   |   |
|                      |   |   |   |   |
| /s/ Kimberly Luff Wakim   |   | Director |   | May 18, 2011 |
| Kimberly Luff Wakim       |   |   |   |   |