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

Date of Report (Date of earliest event reported): November 14, 2011

NAVISTAR INTERNATIONAL CORPORATION

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (630) 753-5000

Not Applicable

(Former name or former address, if changed since last report.)

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 14, 2011, Navistar International Corporation (the “Company”) entered into an agreement (the “Agreement”) with certain stockholders, including Carl C. Icahn (“Icahn”) and certain investment funds affiliated with Icahn (collectively, the “Icahn Group”).

Under the terms of the Agreement, the Company agrees to submit a resolution to its stockholders at the 2012 annual meeting of stockholders (the “2012 Annual Meeting”) that will declassify the Company’s board of directors (the “Board”) and provide for the annual election of directors (the “Declassification Proposal”). Through the date of the Company’s 2013 Annual Meeting, the Company also agrees not to adopt any stockholder rights plan that restricts the ability of the Icahn Group to own up to 14.99% of the Company’s voting securities and, conditioned upon stockholder approval of the Declassification Proposal, not to increase the size of the Board above eleven directors.

The Icahn Group agrees that it shall vote in favor of the directors nominated by the Board for election at the 2012 Annual Meeting and in accordance with the recommendation of the Board regarding the Declassification Proposal and the proposal to ratify the selection of the Company’s auditor. Prior to or at the 2012 Annual Meeting, the Icahn Group agrees, among other things, not to present any proposal for consideration for action by stockholders, propose any nominee for election to the Board or make any statement or announcement that disparages the Company, its officers or its directors. Through the date of the Company’s 2013 Annual Meeting, and conditioned upon stockholder approval of the Declassification Proposal, the Icahn Group further agrees not to acquire in excess of 14.99% of the Company’s voting securities without providing the Company at least ten days’ prior notice of intent to do so.

A copy of the Agreement is filed with this Form 8-K and attached hereto as Exhibit 10.1. The foregoing description of the Agreement does not purport to be complete and is qualified in its entirety by reference to the full text of the Agreement. On November 15, 2011, the Company issued a press release announcing the execution of the Agreement. A copy of the press release is filed with this Form 8-K and attached hereto as Exhibit 99.1.

(d) Exhibits.

SIGNATURE

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 15, 2011

EXHIBIT INDEX