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 9, 2011

WALGREEN CO.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (847) 914-2500

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:

Walgreen Co. plans to distribute the attached informational materials regarding Express Scripts, Inc. to various industry participants and others. A copy of these materials is attached as attached as Exhibit 99.1 hereto. This report shall not be deemed an admission as to the materiality of any of the events described in this Item or in such exhibit.

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Cautionary Note Regarding Forward-Looking Statements

Statements in this report that are not historical, including, without limitation, statements regarding future prescription growth and business retention, are forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995. Words such as “expect,” “likely”, “outlook,” “forecast”, “would,” “could,” “should,” “will,” “project,” “intend,” “plan,” “continue,” “sustain,” “on track,” “believe,” “seek,” “estimate,” “anticipate,” “may,” “possible,” “assume,” variations of such words and similar expressions are intended to identify such forward-looking statements. These forward-looking statements are not guarantees of future performance and involve risks, assumptions and uncertainties, including, but not limited to, the changes in vendor, payer and customer relationships and terms, competition, industry consolidation and the effects thereof, changes in economic and business conditions, risks associated with new business initiatives and activities, failure to obtain new contracts or extensions of existing contracts, and outcomes of legal and regulatory matters. These and other risks, assumptions and uncertainties are described in Item 1A (Risk Factors) of our most recent Annual Report on Form 10-K, which is incorporated herein by reference, and in other documents that we file or furnish with the Securities and Exchange Commission. Should one or more of these risks or uncertainties materialize, or should underlying assumptions prove incorrect, actual results may vary materially from those indicated or anticipated by such forward-looking statements. Accordingly, you are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date they are made. Except to the extent required by law, Walgreens does not undertake, and expressly disclaims, any duty or obligation to update publicly any forward-looking statement after the date of this report, whether as a result of new information, future events, changes in assumptions or otherwise.

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.