UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to Section 13 or 15(d) of the

Securities Exchange Act of 1934

August 17, 2012

Date of Report (Date of earliest event reported)

INERGY, L.P.

(Exact name of registrant as specified in its charter)

Two Brush Creek Boulevard, Suite 200

Kansas City, Missouri 64112

(Address of principal executive offices)

(816) 842-8181

(Registrant’s telephone number, including area code)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

On August 17, 2012, Inergy, L.P. (“NRGY”) issued a press release announcing that its Board of Directors has set the record date and distribution date for the distribution to NRGY unitholders of common units of Suburban Propane Partners, L.P. (“SPH”). As previously announced, on August 1, 2012, NRGY received, as partial consideration for the contribution of its retail propane operations to SPH, approximately 14.2 million SPH common units. Under terms of the contribution agreement, NRGY agreed to distribute on a pro rata basis approximately 14.1 million of the SPH common units to the NRGY unitholders. The full text of the press release is furnished as Exhibit 99.1 to this Current Report on Form 8-K.

In accordance with General Instruction B.2 of Form 8-K, the information furnished pursuant to this Item 7.01 and the related information furnished pursuant to Item 9.01 shall not be deemed to be “filed” for purposes of Section 18 of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), or otherwise subject to the liabilities of that section, nor shall such information be deemed incorporated by reference in any filing under the Securities Act of 1933, as amended, or the Exchange Act, except as shall be expressly set forth by specific reference in such a filing. The information furnished pursuant to Item 7.01 and Item 9.01 shall not be deemed an admission as to the materiality of any information in this Current Report on Form 8-K that is required to be disclosed solely to satisfy the requirements of Regulation FD.

Forward Looking Statements

Information contained in this Current Report on Form 8-K may include certain statements concerning expectations for the future that are forward-looking statements as defined by federal securities law. Such forward-looking statements may include statements preceded by, followed by or that contain forward-looking terminology, including the words “believe,” “expect,” “may,” “should,” “could,” “anticipate,” “estimate,” “intend” or the negation thereof, or similar expressions. Forward-looking statements are subject to a variety of known and unknown risks, uncertainties and other factors that are difficult to predict and many of which are beyond management’s control. Among those is the risk that the anticipated benefits from the closing of transactions contemplated by the Contribution Agreement cannot be fully realized and that the timing of NRGY’s distribution of the SPH common units may be delayed because of factors beyond NRGY’s control. Should one or more of these risks or uncertainties materialize or any underlying assumption proves incorrect, actual results may vary materially from those anticipated, estimated or projected. Among the key factors that could cause actual results to differ materially from those referred to in the forward-looking statements are: weather conditions that vary significantly from historically normal conditions; the general level of petroleum product demand and the availability of propane supplies; the price of propane to the consumer compared to the price of alternative and competing fuels; the demand for high deliverability natural gas storage capacity in the Northeast; Inergy’s ability to successfully implement its business plan; the outcome of rate decisions levied by the Federal Energy Regulatory Commission; Inergy’s ability to generate available cash for distribution to unitholders; and the costs and effects of legal, regulatory and administrative proceedings against, or that may be brought against, Inergy or its subsidiaries. These and other risks and assumptions are described in Inergy’s annual reports on Form 10-K and other reports that are available from the United States Securities and Exchange Commission. Readers are cautioned not to place undue reliance on forward-looking statements, which reflect management’s view only as of the date made. Inergy undertakes no obligation to update any forward-looking statement, except as otherwise required by law.

2

Item 9.01 Financial Statements and Exhibits.

3

Signatures

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

4

Exhibit Index

5