UNDERWRITING AGREEMENT

Exhibit 1.1

Execution Version

INERGY, L.P.

3,000,000 Common Units

UNDERWRITING AGREEMENT

New York, New York

February 21, 2007

UBS S ECURITIES LLC

299 Park Avenue

New York, New York 10171

The undersigned, Inergy, L.P., a Delaware limited partnership (the “ Partnership ”), Inergy Propane, LLC, a Delaware limited liability company (the “ Operating Company ”), and Inergy Midstream, LLC, a Delaware limited liability company (“ Midstream ,” collectively with the Partnership and the Operating Company, the “ Inergy Parties ”), hereby address you as the “ Underwriter ” and hereby confirm their respective agreements with you as set forth below.

As used herein, L & L Transportation, LLC, a Delaware limited liability company (“ L & L Transportation ”), Inergy Transportation, LLC, a Delaware limited liability company (“ Inergy Transportation ”), Inergy Stagecoach II, LLC, a Delaware limited liability company (“ Stagecoach II ”), Inergy Gas Marketing, LLC, a Delaware limited liability company (“ Inergy Gas ”), Inergy Storage, Inc., a Delaware corporation (“ Storage ”), Central New York Oil and Gas Company, LLC, a New York limited liability company (“ CNYOGC ”), Stellar Propane Service, LLC, a Delaware limited liability company (“ Stellar Propane ”), and Inergy Sales & Service, Inc., a Delaware corporation (“ Service Sub ”), are sometimes collectively referred to herein as the “ Operating Subs .”

As used herein, the Inergy Parties, the Operating Subs, Inergy GP, LLC, a Delaware limited liability company (the “ Managing General Partner ”), Inergy Partners, LLC, a Delaware limited liability company (the “ Non-Managing General Partner ” and, together with the Managing General Partner, the “ General Partners ”), are collectively referred to as the “ Inergy Entities .”

1. Description of Common Units . The Partnership proposes to issue and sell to the Underwriter 3,000,000 common units (the “ Firm Units ”) representing limited partner interests in the Partnership (the “ Common Units ”). The Partnership further proposes to grant to the Underwriter the right to purchase up to an additional 450,000 Common Units (the “ Option Units ”) under certain circumstances as provided in Section 3 of this Agreement. The Firm Units and the Option Units are herein sometimes referred to as the “ Units ” and are more fully described in the Final Prospectus hereinafter defined.

2. Purchase, Sale and Delivery of Firm Units . On the basis of the representations, warranties and agreements herein contained, but subject to the terms and conditions herein set forth, the Partnership agrees to sell 3,000,000 Firm Units to the Underwriter, and the Underwriter agrees (a) to purchase from the Partnership, at a purchase price of $30.37 per unit, 3,000,000 Firm Units and (b) to purchase from the Partnership any additional number of Option Units which such Underwriter may become obligated to purchase pursuant to Section 3 hereof.

Delivery of the Firm Units will be in book-entry form through the facilities of The Depository Trust Company, New York, New York (“ DTC ”). Delivery of the documents required by Section 6 hereof with respect to the Units shall be made available at or prior to 9:00 a.m., New York City time, on February 27, 2007 at the office of Vinson & Elkins L.L.P., 1001 Fannin Street, 2300 First City Tower, Houston, TX 77002-6760, or at such other place as may be agreed upon between you and the Partnership (the “ Place of Closing ”), or at such other time and date not later than five full business days thereafter as you and the Partnership may agree, such time and date of payment and delivery being herein called the “ Initial Delivery Date .” Time shall be of the essence, and delivery at the time and place specified pursuant to this Agreement is a further condition of the obligation of the Underwriter hereunder.

The Partnership will deliver the Firm Units to the Underwriter, against payment of the purchase price therefor in Federal (same day) Funds by wire transfer to an account at the bank specified by the Partnership.

The Partnership will cause its transfer agent to deposit the Firm Units pursuant to the Full Fast Delivery Program of the DTC.

It is understood that the Underwriter propose to offer the Units to the public upon the terms and conditions set forth in the Final Prospectus hereinafter defined.

3. Purchase, Sale and Delivery of the Option Units . The Partnership hereby grants an option to the Underwriter to purchase from the Partnership up to 450,000 Option Units on the same terms and conditions as the Firm Units to the extent that the Underwriter sells more than the number of Firm Units in the offering. No Option Units shall be sold or delivered unless the Firm Units previously have been, or simultaneously are, sold and delivered at the same price as the Firm Units.

The option is exercisable by you at any time, in whole or in part, and from time to time, before the expiration of 30 days from the date of the Final Prospectus (or, if such 30th day shall be a Saturday or Sunday or a holiday, on the next day thereunder when The Nasdaq National Market (the “ Nasdaq ”) is open for trading), for the purchase of all or part of the Option Units covered thereby, by notice given by you to the Partnership in the manner provided in Section 12 hereof, setting forth the number of Option Units as to which the Underwriter is exercising the option, and the date of delivery of said Option Units, which date shall not be more than five business days after such notice unless otherwise agreed to by the parties.

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The allocation of the Option Units may be made as required to eliminate the purchase of fractional Units.

Delivery of the Option Units will be in book-entry form through the facilities of DTC. Delivery of the documents required by Section 6 hereof with respect to the Option Units shall be made at the Place of Closing at or prior to 9:00 a.m., New York City time, on the date designated in the notice given by you as provided above, or at such other time and date as you and the Partnership may agree (which may be the same as the Initial Delivery Date), such time and date of payment and delivery being herein called the “ Option Unit Delivery Date .” The Initial Delivery Date and any Option Unit Delivery Date are sometimes each referred to as a “ Delivery Date .” Time shall be of the essence, and delivery at the time and place specified pursuant to this Agreement is a further condition of the obligation of the Underwriter hereunder. On the Option Unit Delivery Date, the Partnership shall provide the Underwriter such representations, warranties, agreements, opinions, letters, certificates and covenants with respect to the Option Units as are required to be delivered on the Initial Delivery Date with respect to the Firm Units.

The Partnership will cause its transfer agent to deposit the Option Units pursuant to the Full Fast Delivery Program of the DTC.

4. Representations, Warranties and Agreements of the Partnership . The Partnership represents and warrants to and agrees with the Underwriter that:

(a) Registration Statement/Prospectus . A registration statement (Registration No. 333-132287) on Form S-3 with respect to the Units, including a related Basic Prospectus has been prepared by the Partnership pursuant to and in conformity with the requirements of the Securities Act of 1933, as amended (the “ 1933 Act ”), and the rules and regulations thereunder (the “ 1933 Act Rules and Regulations ”) of the Securities and Exchange Commission (the “ SEC ”) and has been filed and declared effective by the SEC under the 1933 Act. Such Registration Statement, including any amendments thereto filed prior to the Execution Time, has become effective. The Partnership will file with the SEC a Final Prospectus (as defined below) in accordance with Rule 424(b). As filed, such Final Prospectus shall contain all information required by the 1933 Act and the 1933 Act Rules and Regulations, except to the extent the Underwriter shall agree in writing to a modification, shall be in all substantive respects in the form furnished to you prior to the Execution Time or, to the extent not completed at the Execution Time, shall contain only such specific additional information and other changes (beyond that contained in the Basic Prospectus and any Preliminary Final Prospectus) as the Partnership has advised you, prior to the Execution Time, will be included or made therein. Copies of such registration statement, including any amendments thereto, each related preliminary prospectus contained therein, and the exhibits, financial statements and schedules thereto have heretofore been delivered by the Partnership to the Underwriter. As used in this Agreement:

(i) “ Basic Prospectus ” shall mean the prospectus referred to in paragraph 4(a) above contained in the Registration Statement at the Effective Date.

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(ii) “ Disclosure Package ” means, as of the Execution Time, the most recent Preliminary Final Prospectus, together with (A) each Issuer Free Writing Prospectus filed by the Partnership on or before the Execution Time, and (B) the number of Units, the public offering price for the Units, which will be included on the cover page of the Final Prospectus.

(iii) “ Effective Date ” shall mean each date and time that the Registration Statement, any post-effective amendment or amendments thereto and any Rule 462(b) Registration Statement became or become effective.

(iv) “ Execution Time ” shall mean the date and time that this Agreement is executed and delivered by the parties hereto.

(v) “ Final Prospectus ” shall mean the prospectus supplement relating to the Units that was first filed pursuant to Rule 424(b) after the Execution Time, together with the Basic Prospectus.

(vi) “ Issuer Free Writing Prospectus ” means each “free writing prospectus” (as defined in Rule 405 of the Rules and Regulations) prepared by or on behalf of the Partnership or used or referred to by the Partnership in connection with the offering of the Units.

(vii) “ Preliminary Final Prospectus ” shall mean any preliminary prospectus supplement to the Basic Prospectus which describes the Units and the offering thereof and is used prior to filing of the Final Prospectus, together with the Basic Prospectus.

(vii) “ Registration Statement ” shall mean the registration statement referred to in paragraph 4(a) above, including exhibits and financial statements and any prospectus supplement relating to the Units that is filed with the SEC pursuant to Rule 424(b) and deemed part of such registration statement pursuant to Rule 430A, as amended at the Execution Time and, in the event any post-effective amendment thereto or any Rule 462(b) Registration Statement becomes effective prior to the Initial Delivery Date, shall also mean such registration statement as so amended or such Rule 462(b) Registration Statement, as the case may be.

(ix) “ Rule 462(b) Registration Statement ” shall mean a registration statement and any amendments thereto filed pursuant to Rule 462(b) relating to the offering covered by the registration statement referred to in Section 4(a) hereof.

Any reference to any Preliminary Final Prospectus or the Basic Prospectus shall be deemed to refer to and include any documents incorporated by reference therein pursuant to Form S-3 under the Securities Act as of the date of such Preliminary Final Prospectus or the Basic Prospectus, as the case may be. Any reference to the “ most recent Preliminary Final Prospectus ” shall be deemed to refer to the latest Preliminary Final Prospectus included in the

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Registration Statement or filed pursuant to Rule 424(b) on or prior to the date hereof. Any reference to any amendment or supplement to any Preliminary Final Prospectus or the Basic Prospectus shall be deemed to refer to and include any document filed under the Securities Exchange Act of 1934, as amended (the “ 1934 Act ”), after the date of such Preliminary Final Prospectus or the Basic Prospectus, as the case may be, and incorporated by reference in such Preliminary Final Prospectus or the Basic Prospectus, as the case may be; and any reference to any amendment to the Registration Statement shall be deemed to include the most recent annual report of the Partnership on Form 10-K filed with the SEC pursuant to Section 13(a) or 15(d) of the 1934 Act after the Effective Date that is incorporated by reference in the Registration Statement. The SEC has not issued any order preventing or suspending the use of any Preliminary Final Prospectus or the Basic Prospectus or suspending the effectiveness of the Registration Statement, and no proceeding or examination for such purpose has been instituted or, to the Partnership’s knowledge, threatened by the SEC. The SEC has not notified the Partnership of any objection to the use of the form of the Registration Statement.

(b) No Material Misstatements or Omissions in the Registration Statement . On the Effective Date, the Registration Statement did, and when the Final Prospectus is first filed in accordance with Rule 424(b) and on any Delivery Date, the Final Prospectus will, comply in all material respects with the applicable requirements of the 1933 Act and the 1933 Act Rules and Regulations; on the Effective Date and at the Execution Time, the Registration Statement did not and will not contain any untrue statement of a material fact or omit to state a material fact required to be stated therein or necessary in order to make the statements therein not misleading; and on the date of any filing pursuant to Rule 424(b) and on any Delivery Date, the Final Prospectus (together with any supplement thereto) will not include any untrue statement of a material fact or omit to state a material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading; provided , however , that the Partnership makes no representations or warranties as to the information contained in or omitted from the Registration Statement or the Final Prospectus in reliance upon and in conformity with written information furnished to the Partnership by or on behalf of the Underwriter specifically for inclusion in the Registration Statement or the Final Prospectus (or any supplement thereto), it being understood and agreed that the only such information furnished by the Underwriter consists of the information described as such in Section 15 hereof.

(c) No Material Misstatements or Omissions in the Disclosure Package . (i) The Disclosure Package and the price to the public, the number of Firm Units and the number of Option Units to be included on the cover page of the Final Prospectus, when taken together as a whole, and (ii) each electronic roadshow when taken together as a whole with the Disclosure Package, and the price to the public, the number of Firm Units and the number of Option Units to be included on the cover page of the Final Prospectus do not contain any untrue statement of a material fact or omit to state any material fact necessary in order to make the statements therein, in the light of the circumstances under which they were made, not misleading. The preceding sentence does not apply to statements in or omissions from the Disclosure Package based upon and in conformity with written information furnished to the Partnership by or on behalf of the Underwriter specifically for inclusion in the Registration Statement or the Final Prospectus (or any supplement thereto) therein, it being understood and agreed that the only such information furnished by the Underwriter consists of the information described as such in Section 15 hereof.

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(d) Ineligible Issuer . (i) At the time of filing the Registration Statement and (ii) as of the Execution Time (with such date being used as the determination date for purposes of this clause (ii)), the Partnership was not and is not an Ineligible Issuer (as defined in Rule 405), without taking account of any determination by the SEC pursuant to Rule 405 that it is not necessary that the Partnership be considered an Ineligible Issuer.

(e) Issuer Free Writing Prospectus . Each Issuer Free Writing Prospectus (including, without limitation, any road show that is a free writing prospectus under Rule 433), when considered together with the Disclosure Package as of the Execution Time, did not contain an untrue statement of a material fact or omit to state a material fact necessary to make the statements therein, in the light of the circumstances under which they were made, not misleading. Each Issuer Free Writing Prospectus (including, without limitation, any road show that is a free writing prospectus under Rule 433) does not include any information that conflicts with the information contained in the Registration Statement, including any document incorporated by reference therein that has not been superseded or modified. The foregoing sentence does not apply to statements in or omissions from any Issuer Free Writing Prospectus based upon and in conformity with written information furnished to the Partnership by or on behalf of the Underwriter specifically for inclusion in the Registration Statement or the Prospectus (or any supplement thereto), it being understood and agreed that the only such information furnished by the Underwriter consists of the information described as such in Section 15 hereof.

(f) Other Sales. The Partnership has not sold or issued any Common Units during the six-month period preceding the date of the Initial Delivery Date, other than Common Units issued pursuant to acquisitions, employee benefit plans, qualified options plans or other employee compensation plans or pursuant to outstanding options, rights or warrants described in the Disclosure Package and the Final Prospectus.

(g) Form S-3 . The conditions for the use of Form S-3, as set forth in the General Instructions thereto, have been satisfied.

(h) Formation, Good Standing and Foreign Qualification of the Inergy Entities. Each of the Inergy Entities has been duly formed, with respect to each limited partnership or limited liability company or duly incorporated, with respect to each corporation, and is validly existing as a limited partnership, limited liability company or corporation, as the case may be, in good standing under the laws of its jurisdiction of organization with all necessary partnership, limited liability company or corporate power and authority to own or lease its properties and to conduct its business in all material respects as described in the Disclosure Package and the Final Prospectus (and any amendment or supplement thereto). Each of the Inergy Entities is duly registered or qualified as a foreign entity for the transaction of business under the laws of each jurisdiction in which the character of the business conducted by it or the nature or location of the properties owned or leased by it makes such registration or qualification necessary, except where the failure so to register or qualify would not (i) have a

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material adverse effect on the business, financial condition or results of operations of the Inergy Entities, taken as a whole (“ Material Adverse Effect ”), or (ii) subject the limited partners of the Partnership to any material liability or disability

(i) Ownership of the General Partner Interests in the Partnership . At each Delivery Date, the Managing General Partner and the Non-Managing General Partner will be the sole general partners of the Partnership. The Non-Managing General Partner will own an approximate 1.0% general partner interest in the Partnership and the Managing General Partner owns a non-economic, managing general partner interest in the Partnership; such general partner interests have been duly authorized and validly issued in accordance with the Second Amended and Restated Agreement of Limited Partnership of the Partnership, as amended (the “ Partnership Agreement ”); and each General Partner owns its general partner interest free and clear of all liens, encumbrances, security interests, equities, charges or claims.

(j) Capitalization . At each Delivery Date (assuming that the Underwriter does not purchase the Options Units), the issued and outstanding limited partner interests of the Partnership will consist of 48,293,253 Common Units, 769,941 Special Units, as defined in Amendment No. 3 to the Partnership Agreement (the “ Special Units ”) and the incentive distribution rights, as defined in the Partnership Agreement (the “ Incentive Distribution Rights ”). At the Initial Delivery Date, all outstanding Common Units, Special Units and Incentive Distribution Rights and the limited partner interests represented thereby have been duly authorized and validly issued in accordance with the Partnership Agreement and are fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Sections 17-607 and 17-804 of the Delaware Revised Limited Partnership Act (the “ Delaware LP Act ”).

(k) Ownership of Common Units and Incentive Distribution Rights . Inergy Holdings, L.P., a Delaware limited partnership (“ Holdings ”), owns directly or indirectly 3,787,340 Common Units and 769,941 Special Units and all of the Incentive Distribution Rights of the Partnership, in each case free and clear of all liens, encumbrances (except restrictions on transferability as described in the Disclosure Package and the Final Prospectus), security interests, equities, charges or claims (other than those created by the $25 million Credit Agreement between Inergy Holdings, L.P., a Delaware limited partnership (“ Holdings ”) and Southwest Bank of St. Louis (the “ Term Loan ”) and the credit facility between Holdings and Enterprise Bank & Trust (the “ Credit Facility ”)).

(l) Ownership of Midstream, the Operating Company and the Operating Subs . The Partnership owns, directly or indirectly, 100% of the issued shares of capital stock or membership interests, as applicable, in each of Midstream, the Operating Company and the Operating Subs; such shares of capital stock or membership interests have been duly authorized and validly issued in accordance with the partnership agreement or limited liability company agreement of such entity (collectively, the “ Organizational Agreements ”) and are fully paid (to the extent required under such Organizational Agreements) and non-assessable (except as such non assessability may be affected by Sections 18-607 and 18-804 of the Delaware Limited Liability Company Act (the “ Delaware LLC Act ”) if applicable); and the Partnership owns

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such shares of capital stock or membership interests free and clear of all liens, encumbrances, security interests, equities, charges or claims (other than those securing obligations under the 5-year Credit Agreement dated as of December 17, 2004, as amended, by and among the Partnership and the lenders therein (the “ Credit Agreement ”) and, in the case of the membership interests in the Operating Subs, as applicable, those certain lease arrangements (the “ Lease Arrangements ”) in favor of Fleet Capital Corp., LaSalle National Leasing Corp., Ryder Transportation Services, Ford Motor Credit, Performance Trailer Rental and Leasing, Paccar Leasing of Dallas and Citicorp Leasing, Inc.).

(m) Ownership of the General Partners . At each Delivery Date, Holdings will directly or indirectly own a 100% membership interest in each of the General Partners; such membership interests have been duly authorized and validly issued in accordance with the Organizational Agreements governing such entity and are fully paid (to the extent required under such Organizational Agreement) and nonassessable (except as such nonassessability may be affected by Sections 18-607 and 18-804 of the Delaware LLC Act) and Holdings owns such membership interests free and clear of all liens, encumbrances, security interests, equities, charges or claims.

(n) Valid Issuance of Firm Units . At the Initial Delivery Date, there will be issued to the Underwriter the Firm Units (assuming no purchase by the Underwriter of Option Units on the Initial Delivery Date); at the Initial Delivery Date or the Option Unit Delivery Date, as the case may be, the Firm Units or the Option Units, as the case may be, and the limited partner interests represented thereby, will be duly and validly authorized in accordance with the Partnership Agreement and, when issued and delivered to the Underwriter against payment therefor in accordance with the terms hereof, will be duly and validly issued, fully paid (to the extent required under the Partnership Agreement) and nonassessable (except as such nonassessability may be affected by matters described in Sections 17-607 and 17-804 of the Delaware LP Act).

(o) No Other Subsidiaries . The Partnership does not own or control, directly or indirectly, any corporation, association or other entity other than the subsidiaries listed on Exhibit 21.1 to the Partnership’s Annual Report on Form 10-K for the most recent fiscal year. Neither Inergy Finance Corporation, a Delaware corporation, nor Inergy Canada Company, a Nova Scotia unlimited liability company, is a significant subsidiary within the meaning of Rule 1-02(w) of Regulation S-X. Neither the Partnership nor any of its subsidiaries own, directly or indirectly, any equity or long-term debt securities of any corporation, partnership, limited liability company, joint venture, association or other entity, other than as set forth on Exhibit 21.1 to the Partnership’s Annual Report on Form 10-K for the fiscal year ended September 30, 2005. Other than its ownership of its partnership interest in the Partnership, the Managing General Partner does not own, and as of each Delivery Date will not own, directly or indirectly, any equity or long-term debt securities of any corporation, partnership, limited liability company, joint venture, association or other entity.

(p) No Preemptive Rights, Registration Rights or Options . Except as described in the Disclosure Package and the Final Prospectus, there are no preemptive rights or

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other rights to subscribe for or to purchase, nor any restriction upon the voting or transfer of any capital stock or partnership or membership interests of any of the Inergy Entities, in each case pursuant to the Organizational Agreements or the certificates of limited partnership or formation or incorporation, bylaws and other organizational documents (together with the Organizational Agreements, the “ Organizational Documents ”) or any other agreement or instrument to which any of such entities is a party or by which any one of them may be bound. Neither the filing of the Registration Statement or the Final Prospectus nor the offering, issuance or sale of the Units as contemplated by this Agreement gives rise to any rights for or relating to the registration of any Common Units or other securities of any of the Partnership other than pursuant to that certain Investor Rights Agreement (“ Investor Rights Agreement ”) dated as of January 12, 2001, by and among Inergy Partners, LLC (as predecessor to the Partnership) and the investors named therein and those other rights which have been waived. Except as described in the Disclosure Package and the Final Prospectus and for options granted pursuant to employee benefit plans, qualified unit option plans, or other employee compensation plans, there are no outstanding options or warrants to purchase any capital stock or partnership or membership interests of any of the Inergy Entities.

(q) Authority and Authorization . The Partnership has all requisite power and authority to issue, sell and deliver the Units to be sold by it hereunder in accordance with and upon the terms and conditions set forth in this Agreement, the Partnership Agreement, the Disclosure Package and the Final Prospectus. At each Delivery Date, all corporate, partnership and limited liability company action, as the case may be, required to be taken by the Inergy Entities or any of their stockholders, members or partners for the authorization, issuance, sale and delivery of the Units to be sold by the Partnership hereunder and the consummation of the transactions contemplated by this Agreement shall have been validly taken.

(r) Due Authorization of the Underwriting Agreement . This Agreement has been validly executed and delivered by each of the Inergy Parties.

(s) Enforceability of Other Agreements . At each Delivery Date, each of the Organizational Agreements will have been duly authorized, executed and delivered by the parties thereto and will be a valid and legally binding agreement of such party, enforceable against such party in accordance with its terms; provided that, the enforceability thereof may be limited by bankruptcy, insolvency, fraudulent transfer, reorganization, moratorium and similar laws relating to or affecting creditors’ rights generally and by general principles of equity (regardless of whether such enforceability is considered in a proceeding in equity or at law); and provided, further, that the indemnity, contribution and exoneration provisions contained in any of such agreements may be limited by applicable laws and public policy.

(t) No Conflicts . None of the offering, issuance and sale by the Partnership of the Units, the execution, delivery and performance of this Agreement or the consummation of the transactions contemplated hereby (i) conflicts or will conflict with or constituted, constitutes or will constitute a violation of the Organizational Documents, (ii) constitutes or will constitute a breach or violation of, or a default (or an event which, with notice or lapse of time or both, would constitute such a default) under any indenture, mortgage, deed of trust, loan agreement,

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lease or other agreement or instrument to which any of the Inergy Entities is a party or by which any of them or any of their respective properties may be bound, (iii) violates or will violate any statute, law or regulation or any order, judgment, decree or injunction of any court or governmental agency or body directed to any of the Inergy Entities or any of their properties in a proceeding which any of them or their property is a party, or (iv) results or will result in the creation or imposition of any lien, charge or encumbrance upon any property or assets of any of the Inergy Entities, which breaches, violations, defaults or liens, in the case of clauses (ii), (iii) or (iv), would, individually or in the aggregate, have a Material Adverse Effect.

(u) No Consents . No permit, consent, approval, authorization, order, registration, filing or qualification (“ consent ”) of or with any court, governmental agency or body having jurisdiction over the Inergy Entities or any of their respective properties is required for the offering, issuance and sale by the Partnership of the Units, the execution, delivery and performance of this Agreement or the consummation by the Inergy Entities of the transactions contemplated by this Agreement, except for such consents required under the 1933 Act, the 1933 Act Rules and Regulations, the 1934 Act, and the rules and regulations thereunder (the “ 1934 Act Rules and Regulations ”) and state securities or “Blue Sky” laws and applicable rules and regulations under such laws.

(v) No Default . None of the Inergy Entities is (i) in violation of its Organizational Documents, or (ii) in violation of any law, statute, ordinance, administrative or governmental rule or regulation applicable to it or of any decree of any court or governmental agency or body having jurisdiction over it or (iii) in breach, default (or an event which, with notice or lapse of time or both, would constitute such a default) or violation in the performance of any obligation, agreement or condition contained in any bond, debenture, note or any other evidence of indebtedness or in any agreement, indenture, lease or other instrument to which it is a party or by which it or any of its properties may be bound, which breach, default or violation in the case of clause (ii) or (iii) would, if continued, have a Material Adverse Effect or could materially impair the ability of any of the Inergy Parties to perform its obligations under this Agreement. To the knowledge of the Inergy Parties, no third party to any indenture, mortgage, deed of trust, loan agreement or other agreement or instrument to which any of the Inergy Entities is a party or by which any of them is bound or to which any of their properties is subject, is in default under any such agreement, which breach, default or violation would, if continued, have a Material Adverse Effect.

(w) Conformity of Securities to Descriptions in the Disclosure Package and the Final Prospectus . The Units, when issued and delivered against payment therefor as provided herein, and the Incentive Distribution Rights, will or do as applicable, conform in all material respects to the description thereof contained in the Disclosure Package and the Final Prospectus.

(x) Independent Registered Public Accounting Firm – Ernst & Young. The accountants, Ernst & Young LLP, who have certified certain audited financial statements contained or incorporated by reference in the Registration Statement and the most recent Preliminary Final Prospectus (or any amendment or supplement thereto), are an independent registered public accounting firm with respect to the Partnership and the General Partners as required by the 1933 Act and the 1933 Act Rules and Regulations.

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(y) Financial Statements . The historical financial statements (including the related notes and supporting schedules) contained or incorporated by reference in the Registration Statement, Preliminary Final Prospectus and the Final Prospectus comply as to form in all material respects with the requirements of Regulation S-X under the 1933 Act and present fairly in all material respects the financial position, results of operations and cash flows of the entities purported to be shown thereby on the basis stated therein at the respective dates or for the respective periods to which they apply and have been prepared in accordance with generally accepted accounting principles consistently applied throughout the periods involved, except to the extent disclosed therein. The summary historical and pro forma financial information contained or incorporated by reference in the Registration Statement and the most recent Preliminary Final Prospectus (or any amendment or supplement thereto) and the selected historical information is accurately presented in all material respects and prepared on a basis consistent with the audited and unaudited historical consolidated financial statements and pro forma financial statements, as applicable, from which it has been derived. The pro forma financial statements of the Partnership included or incorporated by reference in the Registration Statement and the most recent Preliminary Final Prospectus (or any amendment or supplement thereto) have been prepared in all material respects in accordance with the applicable accounting requirements of Article 11 of Regulation S-X of the SEC; the assumptions used in the preparation of such pro forma financial statements are, in the opinion of the management of the Managing General Partner, reasonable; and the pro forma adjustments reflected in such pro forma financial statements have been properly applied to the historical amounts in compilation of such pro forma financial statements.

(z) No Material Adverse Change . None of the Inergy Entities has sustained since the date of the latest audited financial statements contained or incorporated by reference in the Registration Statement and the most recent Preliminary Final Prospectus (or any amendment or supplement thereto), any material loss or interference with its business from fire, explosion, flood or other calamity, whether or not covered by insurance, or from any labor dispute or court or governmental action, investigation, order or decree, otherwise than as set forth or contemplated in the Disclosure Package or the Final Prospectus. Except as disclosed in the Disclosure Package or the Final Prospectus, subsequent to the respective dates as of which such information is given in the Registration Statement and the most recent Preliminary Final Prospectus (or any amendment or supplement thereto), (i) none of the Inergy Entities has incurred any liability or obligation, indirect, direct or contingent, or entered into any transactions, not in the ordinary course of business, that, singly or in the aggregate, is material to the Inergy Entities, (ii) there has not been any material change in the capitalization, or material increase in the short-term debt or long-term debt, of the Inergy Entities and (iii) there has not been any material adverse change, or any development involving or which may reasonably be expected to involve, singly or in the aggregate, a prospective material adverse change in or affecting the general affairs, business, prospects, properties, management, condition (financial or other), partners’ capital, stockholders’ equity, net worth or results of operations of the Inergy Entities.

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(aa) Legal Proceedings or Contracts to be Described or Filed . There are no legal or governmental proceedings pending or, to the knowledge of the Inergy Parties, threatened, against any of the Inergy Entities, or to which any of the Inergy Entities is a party, or to which any of their respective properties is subject, that are required to be described in the Registration Statement or the most recent Preliminary Final Prospectus (or any amendment or supplement thereto) which are not adequately disclosed therein, and there are no agreements, contracts, indentures, leases or other instruments that are required to be described in the Registration Statement or Final Prospectus, or to be filed as an exhibit thereto that are not described or filed as required by the 1933 Act.

(bb) Title to Properties . At each Delivery Date, each of the Inergy Entities will have good and indefeasible title to all real property and good title to all personal property described in the Disclosure Package or the Final Prospectus as owned by it, free and clear of all liens, claims, security interests, equities, or other encumbrances except those (i) created, arising under or securing the Credit Agreement; (ii) described in the Disclosure Package or the Final Prospectus or (iii) that do not materially interfere with the use of such properties taken as a whole as described in the Disclosure Package or the Final Prospectus. All real property and buildings held under lease or license by the Operating Subs are held, by the Operating Subs under valid and subsisting and enforceable leases or licenses with such exceptions as do not materially interfere with the use of such properties taken as a whole as they have been used in the past and are proposed to be used in the future as described in the Disclosure Package or the Final Prospectus.

(cc) Permits . At each Delivery Date, each of the Inergy Entities will have such permits, consents, licenses, franchises, certificates and authorizations of governmental or regulatory authorities (“permits”) as are necessary to own its properties and to conduct its business in the manner described in the Disclosure Package or the Final Prospectus, subject to such qualifications as may be set forth in the Disclosure Package or the Final Prospectus and except for such permits which, if not obtained, would not, individually or in the aggregate, have a Material Adverse Effect; at each Delivery Date, each of the Inergy Entities will have fulfilled and performed all its material obligations with respect to such permits which are due to have been fulfilled and performed by such date and no event has occurred which allows, or after notice or lapse of time would allow, revocation or termination thereof or results in any impairment of the rights of the holder of any such permit, except for such revocations, terminations and impairments that would not, individually or in the aggregate, have a Material Adverse Effect, subject in each case to such qualifications as may be set forth in the Disclosure Package or the Final Prospectus; and, except as described in the Disclosure Package or the Final Prospectus, none of such permits contains any restriction that is materially burdensome to the Inergy Entities taken as a whole.

(dd) Books and Records . The Partnership (i) makes and keeps books, records and accounts, which, in reasonable detail, accurately and fairly reflect the transactions and dispositions of assets and (ii) maintains systems of internal accounting controls sufficient to provide reasonable assurances that (A) transactions are executed in accordance with

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management’s general or specific authorization; (B) transactions are recorded as necessary to permit preparation of financial statements in conformity with generally accepted accounting principles and to maintain accountability for assets; (C) access to assets is permitted only in accordance with management’s general or specific authorization; and (D) the recorded accountability for assets is compared with existing assets at reasonable intervals and appropriate action is taken with respect to any differences.

(ee) Disclosure Controls . The Partnership has established and maintains disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the 1934 Act), which are designed to provide reasonable assurance that the information required to be disclosed by the Partnership in reports that it files under the 1934 Act is accumulated and communicated to the Partnership’s management, including its principal executive officer and principal financial officer, as appropriate, to allow timely decisions regarding required disclosure; such disclosure controls and procedures are effective in all material respects to perform the functions for which they were established.

(ff) No Recent Changes to Internal Control Over Financial Reporting . Since the date of the most recent evaluation of such disclosure controls and procedures, there have been no significant changes in internal controls or in other factors that materially affected our internal control over financial reporting.

(gg) Sarbanes Oxley Act of 2002 . There is and has been no failure on the part of the Partnership and, to the Partnership’s knowledge, any of the General Partner’s directors or officers, in their capacities as such, to comply with the provisions of the Sarbanes-Oxley Act of 2002 and the rules and regulations promulgated in connection therewith.

(hh) Tax Returns . Each of the Inergy Entities has filed (or has obtained extensions with respect to) all material federal, state and foreign income and franchise tax returns required to be filed through the date hereof, which returns are complete and correct in all material respects, and has timely paid all taxes shown to be due, if any, pursuant to such returns, other than those (i) which are being contested in good faith or (ii) which, if not paid, would not have a Material Adverse Effect.

(ii) Investment Company . None of the Inergy Entities is now, and after sale of the Units to be sold by the Partnership hereunder and application of the net proceeds from such sale as described in the Final Prospectus under the caption “Use of Proceeds,” none of the Inergy Entities will be, an “investment company” or a company “controlled by” an “investment company” within the meaning of the Investment Company Act of 1940, as amended.

(jj) No Environmental Problems . Each of the Inergy Entities (i) is in compliance with any and all applicable foreign, federal, state and local laws and regulations relating to the protection of human health and safety and the environment or imposing liability or standards of conduct concerning any Hazardous Material (as hereinafter defined) (“ Environmental Laws ”), (ii) has received of all permits required of it under applicable Environmental Laws to conduct its respective businesses, (iii) is in compliance with all terms

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and conditions of any such permit, and (iv) to the knowledge of the Partnership, does not have any liability in connection with the release into the environment of any Hazardous Materials, except where such noncompliance with Environmental Laws, failure to receive required permits, or failure to comply with the terms and conditions of such permits or liability in connection with such releases would not, individually or in the aggregate, have a Material Adverse Effect. The term “ Hazardous Material ” means (A) any “hazardous substance” as defined in the Comprehensive Environmental Response, Compensation and Liability Act of 1980, as amended, (B) any “hazardous waste” as defined in the Resource Conservation and Recovery Act, as amended, (C) any petroleum or petroleum product, (D) any polychlorinated biphenyl and (E) any pollutant or contaminant or hazardous, dangerous or toxic chemical, material, waste or substance regulated under or within the meaning of any other Environmental Law.

(kk) No Labor Dispute . No material labor dispute with the employees of the Inergy Entities exists or, to the knowledge of the Partnership, is imminent.

(ll) Insurance . The Inergy Entities maintain insurance covering their properties, operations, personnel and businesses against such losses and risks as are reasonably adequate to protect them and their businesses in a manner consistent with other businesses similarly situated. None of the Inergy Entities has received notice from any insurer or agent of such insurer that substantial capital improvements or other expenditures will have to be made in order to continue such insurance, and all such insurance is outstanding and duly in force on the date hereof and will be outstanding and duly in force on the Delivery Date.

(mm) Litigation . Except as described in the Disclosure Package or the Final Prospectus, there is (i) no action, suit or proceeding before or by any court, arbitrator or governmental agency, body or official, domestic or foreign, now pending or, to the knowledge of the Partnership, threatened, to which any of the Inergy Entities is or may be a party or to which the business or property of any of the Inergy Entities is or may be subject, (ii) no statute, rule, regulation or order that has been enacted, adopted or issued by any governmental agency or proposed by any governmental agency and (iii) no injunction, restraining order or order of any nature issued by a federal or state court or foreign court of competent jurisdiction to which any of the Inergy Entities is or may be subject, that, in the case of clauses (i), (ii) and (iii) above, is reasonably likely to (A) individually or in the aggregate have a Material Adverse Effect, (B) prevent or result in the suspension of the offer, issuance or sale of the Units, or (C) in any manner draw into question the validity of this Agreement.

(nn) No Distribution of Other Offering Materials . The Partnership has not distributed and, prior to the later to occur of (i) any Delivery Date and (ii) completion of the distribution of the Units, will not distribute, any offering material in connection with the offering, issuance and sale of the Units other than Preliminary Final Prospectus, the Final Prospectus or the Disclosure Package.

(oo) Quotation . The Units are quoted on the Nasdaq.

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(pp) Stabilization . None of the Inergy Entities (i) has taken, and none of such persons shall take, directly or indirectly, any action designed to cause or result in, or which has constituted or which might reasonably be expected to constitute, the stabilization or manipulation of the price of the Common Units to facilitate the sale or resale of the Common Units in violation of any law, rule or regulation or (ii) since the initial filing of the Registration Statement, except as contemplated by this Agreement, (A) has sold, bid for, purchased or paid anyone any compensation for soliciting purchases of the Common Units or (B) has paid or agreed to pay to any person any compensation for soliciting another to purchase any other securities of the Partnership.

(qq) Neither the Partnership nor any of its subsidiaries nor, to the knowledge of the Inergy Parties, any employee or agent of any of the Inergy Parties has made any payment of funds of the Partnership or any of its subsidiaries or received or retained any funds in violation of any law, rule or regulation (including, without limitation, the Foreign Corrupt Practices Act of 1977), which payment, receipt or retention of funds is of a character required to be disclosed in the Registration Statement, any Preliminary Final Prospectus or the Final Prospectus.

Any certificate signed by any officer of any Inergy Party and delivered to you or to counsel for the Underwriter shall be deemed a representation and warranty by such Inergy Party to each Underwriter as to the matters covered thereby.

5. Additional Covenants .

(a) The Partnership covenants and agrees with the Underwriter that:

(i) The Partnership will timely transmit copies of the Preliminary Final Prospectus and the Final Prospectus, and any amendments or supplements thereto, to the SEC for filing pursuant to Rule 424(b) of the 1933 Act Rules and Regulations.

(ii) The Partnership will deliver or make available to the Underwriter, and to counsel for the Underwriter (i) a signed copy of the Registration Statement as originally filed, including copies of exhibits thereto, of any amendments and supplements to the Registration Statement and (ii) a signed copy of each consent and certificate included in, or filed as an exhibit to, the Registration Statement as so amended or supplemented; the Partnership will deliver to the Underwriter as soon as practicable after the date of this Agreement as many copies of the Final Prospectus as the Underwriter may reasonably request for the purposes contemplated by the 1933 Act; if there is a post-effective amendment to the Registration Statement that is not effective under the 1933 Act, the Partnership will use its best efforts to cause th