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): January 5, 2012 (January 5, 2012)

(Exact name of registrant as specified in its charter)

(Address of principal executive offices, including zip code)

Registrant’s telephone number, including area code: (801) 705-7000

(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 (see General Instruction A.2. below):

ITEM 2.02. Results of Operations and Financial Condition.

On January 5, 2012, Ancestry.com Inc. (the “Company”) announced via a press release selected preliminary results of operations for its quarter and year ended December 31, 2011. A copy of the press release is attached as Exhibit 99.1 hereto.

The exhibit contains references to adjusted EBITDA, which is considered a non-GAAP financial measure.

Management believes that adjusted EBITDA is a useful measure of operating performance because it excludes items that the Company does not consider indicative of its core performance. In determining adjusted EBITDA, the Company adjusts net income for such things as interest, taxes, stock-based compensation and certain non-cash and non-recurring items. However, non-GAAP measures such as adjusted EBITDA should be considered in addition to, not as a substitute for or superior to, net income and net cash provided by operating activities, or other financial measures prepared in accordance with GAAP.

Management uses adjusted EBITDA as a measure of operating performance; for planning purposes, including the preparation of the annual operating budget; to allocate resources to enhance the financial performance of the Company’s business; to evaluate the effectiveness of the Company’s business strategies; to provide consistency and comparability with past financial performance; to facilitate a comparison of the Company’s results with those of other companies; and in communications with the Board of Directors concerning the Company’s financial performance. The Company also uses adjusted EBITDA as a factor when determining management’s incentive compensation.

The information in this Item 2.02 (including Exhibit 99.1) shall not be treated as filed for purposes of the Securities Exchange Act of 1934, as amended.

ITEM 9.01 Financial Statements and Exhibits.

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.

INDEX OF EXHIBITS