CONTRIBUTION AGREEMENT

Exhibit 2.3

CONTRIBUTION AGREEMENT

THIS CONTRIBUTION AGREEMENT (this “Agreement”) is made as of this      day of              2007, by and among Lance T. Shaner (“Shaner”), Benjamin W. Hulburt (“B. Hulburt”), Michael J. Carlson (“Carlson”), Jack Shawver (“Shawver”), Thomas F. Shields (“Shields”), Thomas C. Stably (“Stably”), Christopher K. Hulburt (“C. Hulburt”), PennTex Energy Inc., a Delaware corporation (“PennTex Energy”), and Rex Energy Corporation, a Delaware corporation (“Rex”).

W I T N E S S E T H:

WHEREAS, Shaner is the sole shareholder of PennTex Resources Illinois, Inc., a Delaware corporation (“PennTex Illinois”), and desires to contribute (the “PennTex Illinois Contribution”) all of the outstanding shares of common stock, $0.01 par value, of PennTex Illinois (the “PennTex Illinois Shares”) to Rex in exchange for the number of shares of Rex common stock, $0.001 par value (“Rex Common Stock”), set forth next to his name under PennTex Illinois Contribution in Schedule A;

WHEREAS, Shaner and B. Hulburt are the shareholders of Rex Operating Corp., a Delaware corporation (“Rex Operating”), and each desires to contribute (collectively, the “Rex Operating Contribution”) all of his shares of common stock, $1.00 par value, of Rex Operating (the “Rex Operating Shares”) to Rex in exchange for the number of shares of Rex Common Stock set forth next to his name under Rex Operating Contribution in Schedule A;

WHEREAS, Shaner, B. Hulburt, Carlson, Shawver, Shields, Stably, and C. Hulburt are the members of Rex Energy IV, LLC, a Delaware limited liability company (“Rex IV”), owning fifty percent (50%), fifteen percent (15%), seven percent (7%), seven percent (7%), seven percent (7%), seven percent (7%), seven percent (7%), respectively, of the limited liability company interest in Rex IV (the “Rex IV LLC Interest”), and each desires to contribute (collectively, the “Rex IV Contribution”) all of his Rex IV LLC Interest to Rex in exchange for the number of shares of Rex Common Stock set forth next to his name under Rex IV in Schedule A;

WHEREAS, Shaner is the sole limited partner of PennTex Resources LP, a Texas limited partnership formerly known as S.P. Penntex Energy L.P. (“PennTex LP”), owning ninety-nine percent (99%) of the partnership interest in PennTex LP (the “PennTex LP Partnership Interest”), and Shaner desires to contribute (the “PennTex LP Contribution”) all of his PennTex LP Partnership Interest to Rex in exchange for the number of shares of Rex Common Stock as set forth next to his name under PennTex LP Contribution in Schedule A;

WHEREAS, Shaner is the sole shareholder of PennTex Energy, Inc., a Delaware corporation (“PennTex Energy”), and desires to contribute (the “PennTex Energy Contribution”) all of the outstanding shares of common stock, $1.00 par value, of PennTex Energy (the “PennTex Energy Shares”) to Rex in exchange for the number of shares of Rex Common Stock set forth next to his name under PennTex Energy Contribution in Schedule A;

WHEREAS, in connection with the PennTex Illinois Contribution, the Rex Operating Contribution, the Rex IV Contribution, the PennTex LP Contribution and the PennTex Energy Contribution (collectively, the “Contributions”) and as an overall plan, the following transactions will also occur (collectively, the “Related Transactions”): (i) Douglas Oil & Gas Limited Partnership, a Delaware limited partnership (“Douglas Oil & Gas”), Douglas Westmoreland Limited Partnership, a Delaware limited partnership (“Douglas Westmoreland”), Midland Exploration Limited

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Partnership, a Delaware limited partnership (“Midland”), Rex Energy Limited Partnership, a Delaware limited partnership (“Rex I”), Rex Energy II Limited Partnership, a Delaware limited partnership (“Rex II”), Rex Energy II Alpha Limited Partnership, a Delaware limited partnership (“Rex II Alpha”), and Rex Energy Royalties Limited Partnership, a Delaware limited partnership (“Rex Royalties”), will merge with and into Rex Energy I, LLC, a Delaware limited liability company (“Rex Energy I”), with the holders of the partnership interests in Douglas Oil & Gas, Douglas Westmoreland, Midland, Rex I, Rex II, Rex II Alpha and Rex Royalties receiving shares of Rex Common Stock (the “LP Mergers”); (ii) New Albany-Indiana, LLC, a Delaware limited liability company (“New Albany-Indiana”), and Rex Energy III LLC, a Delaware limited liability company (“Rex III”), will merge with and into Rex Energy I (the “LLC Mergers”), with the holders of the limited liability company interests in New Albany-Indiana and Rex III receiving shares of Rex Common Stock; and (iii) Rex Energy will consummate an initial public offering (the “IPO”) of the Rex Common Stock; and

WHEREAS, for U.S. federal income tax purposes (and state, local and foreign tax purposes where applicable), Shaner, B. Hulburt, Carlson, Shawver, Shields, Stably, C. Hulburt, PennTex Energy and Rex intend for, and will report the PennTex Illinois Contribution, the Rex Operating Contribution, the Rex IV Contribution, the PennTex LP Contribution, the PennTex Energy Contribution, the LP Mergers, the LLC Mergers and the IPO as being pursuant to a plan with the result that each is part of an exchange that is tax-free under Section 351 of the Internal Revenue Code of 1986, as amended (the “Code”);

NOW, THEREFORE, in consideration of the premises and the mutual covenants and agreements herein contained, the receipt and sufficiency of which are hereby acknowledged, and intending to be legally bound hereby, the parties hereto agree as follows:

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IN WITNESS WHEREOF, each of the parties to this Agreement has executed this Agreement as of the date first above written.

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SCHEDULE A

PennTex Illinois Contribution

Rex Operating Contribution

PennTex LP Contribution

Rex IV Contribution

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PennTex Energy Contribution

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