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): October 26, 2012 (October 24, 2012)

ANCESTRY.COM INC.

(Exact name of registrant as specified in its charter)

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

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 October 24, 2012, Ancestry.com Inc. (the “Company”) announced via a press release its preliminary results of operations for its quarter ended September 30, 2012. A copy of the press release is attached as Exhibit 99.1 hereto. The exhibit contains references to adjusted EBITDA and free cash flow, which are considered non-GAAP financial measures.

Management believes that adjusted EBITDA and free cash flow are useful measures of operating performance because they exclude items that the Company does not consider indicative of its core performance. In the case of adjusted EBITDA, the Company adjusts net income for such things as interest, income taxes, stock-based compensation and certain non-cash and non-recurring items. Free cash flow subtracts from adjusted EBITDA the capitalization of content databases, purchases of property and equipment, and cash paid for income taxes and interest. However, these non-GAAP measures 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. A reconciliation to the GAAP equivalents of these non-GAAP measures is contained in the press release and is also posted on the Company’s website.

Management uses adjusted EBITDA and free cash flow as measures 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 and has used free cash flow as factors when determining management’s incentive compensation.

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

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