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                                                                     EXHIBIT 5.1


                               HALE AND DORR LLP
                               COUNSELLORS AT LAW

                 60 STATE STREET, BOSTON, MASSACHUSETTS  02109
                        617-526-6000 . FAX 617-526-5000


                                   August 13, 1999



     Re:  Boston Communications Group, Inc. Non-qualified Stock Options
          -------------------------------------------------------------
          pursuant to written option agreements
          -------------------------------------

Ladies and Gentlemen:

     This opinion is furnished to you in connection with a Registration
Statement on Form S-8 (the "Registration Statement") to be filed with the
Securities and Exchange Commission (the "Commission") under the Securities Act
of 1933, as amended (the "Securities Act"), for the registration of 110,000
shares of Common Stock, $.01 par value per share (the "Shares"), of Boston
Communications Group, Inc., a Massachusetts corporation (the "Company"),
issuable pursuant to written option agreements.

     We have examined the Restated Articles of Organization and the Restated By-
laws of the Company, each as amended to date, and originals, or copies certified
to our satisfaction, of all pertinent records of the meetings of the directors
and stockholders of the Company, the Registration Statement and such other
documents relating to the Company as we have deemed material for the purposes of
this opinion.

     In our examination of the foregoing documents, we have assumed the
genuineness of all signatures and the authenticity of all documents submitted to
us as originals, the conformity to original documents of all documents submitted
to us as copies, the authenticity of the originals of such latter documents and
the legal competence of all signatories to such documents.

     We express no opinion herein as to the laws of any state or jurisdiction
other than the state laws of the Commonwealth of Massachusetts and the federal
laws of the United States of America.

     Based upon and subject to the foregoing, we are of the opinion that the
Company has duly authorized for issuance the Shares covered by the Registration
Statement to be issued pursuant to the written option agreements, as described
in the Registration Statement, and the Shares, when issued and paid for in
accordance with the terms of the written option agreements will be validly
issued, fully-paid and nonassessable.



WASHINGTON, D.C.                    BOSTON, MA                       LONDON, UK*
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             HALE AND DORR LLP INCLUDES PROFESSIONAL CORPORATIONS
 *BROBECK HALE AND DORR INTERNATIONAL (AN INDEPENDENT JOINT VENTURE LAW FIRM)
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Boston Communications Group, Inc.
August 13, 1999
Page 2


     It is understood that this opinion is to be used only in connection with
the offer and sale of the Shares while the Registration Statement is in effect.

     This opinion is based upon currently existing statutes, rules, regulations
and judicial decisions, and we disclaim any obligation to advise you of any
change in any of these sources of law or subsequent legal or factual
developments which might affect any matters or opinions set forth herein.

     Please note that we are opining only as to the matters expressly set forth
herein, and no opinion should be inferred as to any other matters.

     We hereby consent to the filing of this opinion with the Commission as an
exhibit to the Registration Statement in accordance with the requirements of
Item 601(b)(5) of Regulation S-K under the Securities Act.  In giving such
consent, we do not hereby admit that we are in the category of persons whose
consent is required under Section 7 of the Securities Act or the rules and
regulations of the Commission.


                                          Very truly yours,


                                           /s/ Hale and Dorr LLP
                                          -------------------------
                                          HALE AND DORR LLP