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

November 16, 2011

(Date of Report)

November 8, 2011

(Date of earliest event reported)

International Paper Company

(Exact name of registrant as specified in its charter)

Commission File Number 1-3157

Registrant’s telephone number, including area code: (901) 419-7000

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 November 16, 2011, International Paper Company (the “Company”) entered into a supplemental indenture (the “Supplemental Indenture”) to the indenture, dated as of April 12, 1999, between the Company and The Bank of New York Mellon Trust Company, N.A. (as successor to The Bank of New York Mellon (formerly known as The Bank of New York)), as trustee (together with the Supplemental Indenture, the “Indenture”). Pursuant to the Indenture, the Company issued and sold $900,000,000 aggregate principal amount of 4.75% Notes due 2022 and $600,000,000 aggregate principal amount of 6.00% Notes due 2041 (collectively, the “Notes”). The Notes were sold pursuant to an effective shelf registration statement (the “Registration Statement”) on Form S-3, File No. 333-157573, which became effective upon filing with the Securities and Exchange Commission on February 27, 2009. The closing of the sale of the Notes occurred on November 16, 2011. The Supplemental Indenture with respect to the Notes (including the form of Notes) is filed as Exhibit 4.1 hereto and is incorporated by reference herein.

In connection with the issuance and sale of the Notes, the Company entered into an underwriting agreement (the “Underwriting Agreement”), dated November 8, 2011, by and among the Company and BNP Paribas Securities Corp., Deutsche Bank Securities Inc., HSBC Securities (USA) Inc., RBS Securities Inc. and UBS Securities LLC, as representatives of the underwriters named in Schedule A thereto. A copy of the Underwriting Agreement is filed as Exhibit 1.1 hereto.

A copy of the opinion of Debevoise & Plimpton LLP relating to the validity of the Notes is filed as Exhibit 5.1 hereto.

The exhibits to this Current Report on Form 8-K are hereby incorporated by reference into the Registration Statement.

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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.

Date: November 16, 2011

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EXHIBIT INDEX

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