COMMON UNIT REDEMPTION AGREEMENT

Exhibit 10.4

COMMON UNIT REDEMPTION AGREEMENT

     This COMMON UNIT REDEMPTION AGREEMENT (this “Agreement”), is made and entered into as of December 11, 2007, by and between Williams Partners L.P., a Delaware limited partnership (the “Partnership”) and Williams Partners GP LLC , a Delaware limited liability company (the “Holder”).

     WHEREAS, as of the date hereof, the Holder owns 4,163,527 common units representing limited partner interests in the Partnership (the “Common Units”), including Common Units issued to the Holder by the Partnership pursuant to the Purchase and Sale Agreement, dated November 30, 2007, among the Partnership, the Holder and the other parties named therein;

     WHEREAS, the Partnership entered into an underwriting agreement, dated December 5, 2007 (the “Underwriting Agreement”), with Lehman Brothers Inc., Citigroup Global Markets Inc., and Merrill Lynch & Co., as representatives of the underwriters listed on schedule 1 thereto (collectively, the “Underwriters”) pursuant to which the Partnership is publicly offering (the “Public Offering”) for cash (i) 9,250,000 Common Units and (ii) in the event the Underwriters exercise their over-allotment option pursuant to the Underwriting Agreement (the “Over-Allotment Option”), up to an additional 1,387,500 Common Units (the “Option Units”), in each case, pursuant to the Partnership’s registration statement on Form S-3 (File No. 333-137562) (as amended to the date hereof, the “Registration Statement”) and a prospectus supplement, dated the date hereof (together with the base prospectus included in the Registration Statement, the “Prospectus”), filed under Rule 424(b) under the Securities Act (as defined herein); and

     WHEREAS, upon any exercise by the Underwriters of the Over-Allotment Option, in whole or in part, the Holder desires to transfer to the Partnership, and the Partnership desires to redeem from the Holder, that number of Common Units (the “Redemption Units”) equal to the number of Option Units to be sold by the Partnership to the Underwriters upon such exercise, up to an aggregate of 1,387,500 Common Units, upon the terms and conditions hereinafter set forth. !

     NOW THEREFORE, in consideration of the mutual covenants, conditions and agreements set forth herein, and for good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto agree as follows:

     1.  Redemption of Units . Upon the Option Closing Date (as defined below), and subject to the terms and conditions and in reliance on the representations and warranties herein set forth, the Holder agrees to transfer to the Partnership, and the Partnership agrees to redeem from the Holder, up to an aggregate of 1,387,500 Common Units, at a price per unit of $36.24 (the “Per Unit Redemption Price”), which price is equal to the net proceeds per unit received by the Partnership in the Public Offering, after underwriting discounts and commissions, but before expenses, a number of Common Units (the “Redemption Units”) equal to the number of Option Units purchased from the Partnership by the Underwriters (the “Redemption”).

          1.1 The closing (the “Closing”) of the Redemption shall take place at such place and such time so as to coincide with the closing of the Underwriters’ purchase of the Option Units (the “Option Closing Date”) from the Partnership in the Public Offering.

          1.2 At the Closing, the Holder shall assign and transfer to the Partnership all its right, title and interest in and to the Redemption Units, free and clear of all liens or other limitations or restrictions and deliver to the Partnership the certificate or certificates representing such Redemption Units, duly endorsed in blank or accompanied by separate stock powers so endorsed. The Holder shall execute the certificate of transfer on the back of the certificate or certificates representing the Redemption Units.

          1.3 At the Closing, the Partnership shall pay an amount equal to (i) the Per Unit Redemption Price multiplied by (ii) the number of Redemption Units (the “Aggregate Redemption Price”) by wire transfer of immediately available funds to an account of the Holder furnished to the Partnership.

          1.4 The Partnership hereby acknowledges and agrees that, by executing and delivering this Agreement and consummating the transactions contemplated hereby, the Holder is not waiving, in whole or in part, any registration rights it has pursuant to Section 7.12 of the Amended and Restated Agreement of Limited Partnership of the Partnership dated as of August 23, 2005, as amended (the “Partnership Agreement”), with respect to any Common Units held by the Holder that are not redeemed subject to this Agreement, including but not limited to the Holder’s right, as exercised by a registration request, to cause the Partnership to effect the registration under the Securities Act of all Common Units owned by the Holder pursuant to the terms and conditions of the Partnership Agreement.

          1.5 If the Underwriters do not exercise the Over-Allotment Option, then no Redemption will occur pursuant to this Agreement.

     2.  Representations and Warranties of Holder . The Holder hereby represents and warrants to, and agrees with the Partnership, as applicable, that:

          2.1 Existence and Power . The Holder is a limited liability company duly organized, validly existing and in good standing under the laws of the State of Delaware and has all requisite limited liability company power and authority to execute and deliver this Agreement, consummate the transactions and perform each of its obligations contemplated hereby.

          2.2 Authority; Approvals . (a) The execution and delivery of this Agreement by the Holder, the consummation by the Holder of each of the transactions and the performance by the Holder of its obligations contemplated hereby have been duly and properly authorized by all necessary limited liability company action on the part of the Holder. This Agreement has been duly executed and delivered by the Holder, and, assuming the accuracy of the representations and warranties of the Partnership in Section 3 hereof, constitutes the valid and legally binding obligation of the Holder, enforceable against the Holder in accordance with its terms, subject, (i) as to enforceability, to bankruptcy, insolvency, reorganization, moratorium and other similar laws of general applicability relating to or affecting creditors’ rights and to

general principles of equity (regardless of whether such enforceability is considered in a proceeding in equity or at law) and (ii) to equitable principles of general applicability relating to the availability of specific performance, injunctive relief, or other equitable remedies.

               (b) The execution and delivery of this Agreement by the Holder and the consummation of each of the transactions and the performance of each of the obligations contemplated hereby (i) do not conflict with, violate or breach (whether with or without notice or a lapse of time or both), require the consent of any Person to or otherwise result in a material detriment to the Holder under, (A) its organizational documents or (B) any agreement to which it is a party or by which its assets or property is bound or any law or order applicable to it, in the case of clause (B), which conflicts, violations, breaches or material detriments could reasonably be expected to prevent the consummation of any of the transactions contemplated hereby or have a material adverse effect on the business, properties or condition (financial or otherwise) of the Holder; and (ii) do not impose any penalty or other onerous condition on the Holder that could reasonably be expected to prevent the consummation of any of the transactions contemplated hereby. As used in this Agreement, the term “Person” means a natural person, corporation, limited liability company, venture, partnership, trust, unincorporated organization, association or other entity.

               (c) No approval from any Governmental Entity is required with respect to the Holder in connection with the execution and delivery by the Holder of this Agreement, the performance by the Holder of its obligations hereunder or the consummation by the Holder of the transactions contemplated hereby, except for any such approval the failure of which to be made or obtained (i) has not impaired and could not reasonably be expected to impair the ability of the Holder to perform its obligations under this Agreement in any material respect, and (ii) could not reasonably be expected to delay, in any material respect, or prevent the consummation of any of the transactions contemplated by this Agreement. As used in this Agreement, the term “Governmental Entity” means any agency, bureau, commission, authority, department, official, political subdivision, tribunal or other instrumentality of any government, whether (i) regulatory, administrative or otherwise; (ii) federal, state or local; or (iii) domestic or foreign.

          2.3 Ownership of Redemption Units . The Holder is the record and beneficial owner of the Redemption Units, free and clear of any lien and any other limitation or restriction with full right and authority to deliver the same hereunder, and will transfer and deliver to the Partnership on the Option Closing Date valid title to the Redemption Units, free and clear of any lien and any such other limitation or restriction.

          2.4 Independent Investigation . The Holder (a) has the requisite knowledge, sophistication and experience in order to fairly evaluate a disposition of the Redemption Units, including the risks associated therewith, and (b) has adequate information and has made its own independent investigation and evaluation to the extent it deems necessary or appropriate concerning the properties, business and financial condition of the Partnership to make an informed decision regarding the transfer of the Redemption Units pursuant to this Agreement.

     3.  Representations and Warranties of the Partnership . The Partnership hereby represents and warrants to, and agrees with the Holder, that:

          3.1 Existence and Power . The Partnership is a limited partnership duly organized, validly existing and in good standing under the laws of the State of Delaware and has all requisite limited partnership power and authority to execute and deliver this Agreement, consummate the transactions and perform each of its obligations contemplated hereby.

          3.2 Authority; Approvals . (a) The execution and delivery of this Agreement by the Partnership, the consummation by the Partnership of each of the transactions and the performance by the Partnership of each of its obligations contemplated hereby have been duly and properly authorized by all necessary partnership action on the part of the Partnership. This Agreement has been duly executed and delivered by the Partnership and, assuming the accuracy of the representations and warranties of the Holder in Section 2 hereof, constitutes the valid and legally binding obligation of the Partnership, enforceable against it in accordance with its terms, subject, (i) as to enforceability, to bankruptcy, insolvency, reorganization, moratorium and other similar laws of general applicability relating to or affecting creditors’ rights and to general principles of equity (regardless of whether such enforceability is considered in a proceeding in equity or at law) and (ii) to equitable principles of general applicability relating to the availability of specific performance, injunctive relief, or other equitable remedies.

               (b) The execution and delivery of this Agreement by the Partnership and the consummation of each of the transactions and the performance of each of the obligations contemplated hereby (i) do not conflict with, violate or breach (whether with or without notice or a lapse of time or both), require the consent of any Person to or otherwise result in a material detriment to the Partnership under, (A) its organizational documents or (B) any agreement to which it is a party or by which its assets or property i