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) September 26, 2012

DELTEK, INC.

(Exact name of registrant as specified in its charter)

(703) 734-8606

(Registrant’s telephone number, including area code)

Section 8 – Other Events

As previously disclosed in the Notice of Written Consent and Appraisal Rights and Information Statement dated September 12, 2012 (the “Information Statement”), following the announcement by Deltek, Inc. (“Deltek” or the “Company”) of its entry into the Agreement and Plan of Merger, dated August 26, 2012, by and among Deltek, Project Diamond Holdings Corporation (“Parent”) and Project Diamond Merger Corp. (“Merger Sub”) (the “Merger Agreement”), a putative class action lawsuit, entitled Bushansky v. Deltek, Inc. et al., Case No. 7827-12-VCP, was filed against Deltek, the board of directors of Deltek, Thoma Bravo, L.L.C., Parent and Merger Sub in the Court of Chancery of the State of Delaware, New Castle County. On September 26, 2012, the Company and the other defendants reached an agreement-in-principle with the plaintiff regarding the settlement of this lawsuit. In connection with the settlement, the Company agreed to supplement the Information Statement and make additional disclosures to stockholders in connection with the transactions contemplated by the Merger Agreement (such supplement, the “Information Statement Supplement”). The Information Statement Supplement is attached as Exhibit 99.1 hereto and is incorporated herein by reference.

Section 9 – Financial Statements and Exhibits

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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.

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EXHIBIT INDEX

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