Exhibit 5.1

HOGAN & HARTSON L.L.P.
COLUMBIA SQUARE
555 THIRTEENTH STREET, N.W.
WASHINGTON, D.C. 20004-1109
TEL (202) 637-5600
FAX (202) 637-5910
WWW.HHLAW.COM

April 3, 2002

Board of Directors
Arbitron Inc.
142 West 57th Street
New York, New York 10019

Ladies and Gentlemen:

     We are acting as counsel to Arbitron Inc., a Delaware corporation (the “Company”), in connection with its registration statement on Form S-8, as amended (the “Registration Statement”), filed with the Securities and Exchange Commission relating to the proposed public offering of up to 1,000,000 shares of the Company’s common stock, par value $0.50 per share (the “Shares”), issuable pursuant to the Arbitron Inc. 2001 Broad Based Stock Incentive Plan (the “Plan”). This opinion letter is furnished to you at your request to enable you to fulfill the requirements of Item 601(b)(5) of Regulation S-K, 17 C.F.R. § 229.601(b)(5), in connection with the Registration Statement.

     For purposes of this opinion letter, we have examined copies of the following documents:

1.	An executed copy of the Registration Statement.
2.	A copy of the Plan, as certified by an Assistant Secretary of the Company on the date herof as being complete, accurate and in effect.
3.	The Certificate of Incorporation of the Company, as certified by the Secretary of the State of the State of Delaware on April 2, 2002 and by an Assistant Secretary of the Company on the date hereof as being complete, accurate and in effect.
4.	The Bylaws of the Company, as certified by an Assistant Secretary of the Company on the date hereof as being complete, accurate and in effect.
5.	Resolutions of the Board of Directors of the Company adopted at a meeting held on March 30, 2001, as certified by an Assistant Secretary of the Company on the date hereof as being complete, accurate, and in effect, relating to the authorization and approval of the Plan.
6.	Resolutions of the Board of Directors of the Company adopted at a meeting held on May 30, 2001, as certified by an Assistant Secretary of the Company on the date hereof as being complete, accurate, and in effect, relating to the issuance and sale of the Shares and arrangements in connection therewith.

     In our examination of the aforesaid documents, we have assumed the genuineness of all signatures, the legal capacity of all natural persons, the accuracy and completeness of all documents submitted to us, the authenticity of all original documents, and the conformity to authentic original documents of all documents submitted to us as copies (including telecopies). This opinion letter is given, and all statements herein are made, in

the context of the foregoing.

     This opinion letter is based as to matters of law solely on the Delaware General Corporation Law, as amended. We express no opinion herein as to any other laws, statutes, ordinances, rules or regulations. As used herein, the term “Delaware General Corporation Law, as amended” includes the statutory provisions contained therein, all applicable provisions of the Delaware Constitution and reported judicial decisions interpreting these laws.

     Based upon, subject to and limited by the foregoing, we are of the opinion that following (i) effectiveness of the Registration Statement, (ii) issuance of the Shares in the manner and on the terms described in the Registration Statement and the Plan, and (iii) receipt by the Company of the consideration for the Shares specified in the Plan, the Shares will be validly issued, fully paid and nonassessable.

     This opinion letter has been prepared for your use in connection with the Registration Statement and speaks as of the date hereof. We assume no obligation to advise you of any changes in the foregoing subsequent to the delivery of this opinion letter.

     We hereby consent to the filing of this opinion letter as Exhibit 5.1 to the Registration Statement and to the reference to this firm under the caption “Legal Matters” in the prospectus constituting a part of the Registration Statement. In giving this consent, we do not thereby admit that we are an “expert” within the meaning of the Securities Act of 1933, as amended.

Very truly yours,

/s/ Hogan & Hartson L.L.P.

HOGAN & HARTSON L.L.P.