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): March 8, 2013

Arbitron Inc.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: 410-312-8000

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:

Item 8.01. Other Events.

On March 8, 2013, Arbitron Inc. (the “Company”) received a request for additional information and documentary materials (a “Second Request”) from the Federal Trade Commission (“FTC”) regarding the proposed merger of TNC Sub I Corporation (“Merger Sub”), a wholly owned subsidiary of Nielsen Holdings, N.V. (“Nielsen”) with and into the Company (the “Merger”). Nielsen also received a similar Second Request. The Second Requests were issued under the notification requirements of the Hart-Scott-Rodino Antitrust Improvements Act of 1976 (“HSR Act”). The effect of the Second Requests is to extend the waiting period imposed by the HSR Act until 30 days after the Company and Nielsen have substantially complied with the Second Requests, unless that period is extended voluntarily by the parties or terminated sooner by the FTC. The Company intends to respond expeditiously to the Second Request and continue to work cooperatively with the FTC in connection with this review. Completion of the acquisition remains subject to the expiration or termination of the waiting period under the HSR Act, customary closing conditions and approval by the Company’s stockholders.

Additional Information and Where to Find It:

In connection with the Merger, the Company filed a preliminary proxy statement with the Securities and Exchange Commission (the “SEC”) on January 18, 2013. Investors are urged to read the preliminary proxy statement, the definitive proxy statement and any other relevant documents filed by the Company with the SEC when they become available, because they will contain important information about the Merger. The Company will mail the definitive proxy statement to its shareholders as of the record date of the special meeting to vote on the proposed Merger transaction. In addition, Investors may obtain free copies of the preliminary proxy statement and the definitive proxy statement, when it becomes available, as well as other filings containing information about the Company, without charge, at the SEC’s Internet site (http://www.sec.gov). These documents may also be obtained for free from the Company’s Investor Relations web site (http://www.arbitron.com/investors) or by directing a request to the Company at: Arbitron Inc., 9705 Patuxent Woods Drive, Columbia, Maryland 21046.

The Company and its directors and executive officers and other members of management and employees are potential participants in the solicitation of proxies from the Company’s stockholders in respect of the proposed transaction.

Information regarding the Company’s directors and executive officers is available in the Company’s proxy statement for its 2012 annual meeting of stockholders, filed with the SEC on April 12, 2012. Additional information regarding the interests of such potential participants in the proposed transaction is included in the preliminary proxy statement filed with the SEC on January 18, 2013, and will be set forth in the definitive proxy statement to be filed by the Company with the SEC.

Forward Looking Statements:

This written communication includes information that could constitute forward-looking statements made pursuant to the safe harbor provision of the Private Securities Litigation Reform Act of 1995. These statements may be identified by words such as “will”, “expect”, “should”, “could”, “shall” and similar expressions. These statements are subject to risks and uncertainties concerning Nielsen’s proposed acquisition of the Company, the Company’s expected financial performance, as well as the Company’s strategic and operational plans and actual results and events could differ materially from what presently is expected. The potential risks and uncertainties include the possibility that the transaction will not close or that the closing may be delayed; the possibility that the Company may be unable to obtain stockholder approval as required for the transaction or that the other conditions to the closing of the transaction may not be satisfied; the transaction may involve unexpected costs, liabilities or delays; the outcome of any legal proceedings related to the transaction; the occurrence of any event, change or other circumstances that could give rise to the termination of the transaction agreement; general economic conditions; conditions in the markets Nielsen and the Company are engaged in; behavior of customers, suppliers and competitors (including their reaction to the transaction); technological developments; as well as legal and regulatory rules affecting Nielsen’s and the Company’s business and specific risk factors discussed in other releases and public filings made by Nielsen and the Company (including the their respective filings with the SEC). This list of factors is not intended to be exhaustive. Such forward-looking statements only speak as of the date of this written communication, and we assume no obligation to update any written or oral forward-looking statement made by us or on our behalf as a result of new information, future events, or other factors.

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.