Exhibit 5.1
                           [Ropes & Gray Letterhead]



                                       April 1, 1998


State Street Corporation
225 Franklin Street
Boston, Massachusetts 02110

State Street Capital Trust I
c/o State Street Bank and Trust
  Company, N.A.
61 Broadway, 15th Floor
New York, New York  10005

State Street Capital Trust II
c/o State Street Bank and Trust
  Company, N.A.
61 Broadway, 15th Floor
New York, New York  10005

State Street Capital Trust III
c/o State Street Bank and Trust
  Company, N.A.
61 Broadway, 15th Floor
New York, New York  10005

      Re:  Registration Statement on Form S-3 (Registration No. 333-_____) of
           State Street Corporation, State Street Capital Trust I, State Street
           Capital Trust II, and State Street Capital Trust III and Post-
           Effective Amendment No. 1 to Registration Statement on Form S-3
           (Registration No. 333-2143)
           --------------------------------------------------------------------

Ladies and Gentlemen:

     You have asked our opinion concerning (a) the proposed issue by State
Street Corporation, a Massachusetts corporation (the "Company"), of up to
$350,000,000 aggregate amount (exclusive of the amount of any guarantees) of (i)
senior debt securities (the "Senior Debt Securities") consisting of senior
unsecured debentures, notes and/or other evidences of indebtedness, in one or
more series, to be issued under the Senior Indenture between the Company and
U.S. Bank Trust National Association, as successor trustee, dated as of 

 
State Street Corporation
State Street Capital Trust I
State Street Capital Trust II
State Street Capital Trust III           -2-                      April 1, 1998

August 2, 1993 (the "Senior Indenture"), (ii) subordinated debt securities (the
"Subordinated Debt Securities" and, together with the Senior Debt Securities,
the "Debt Securities") consisting of subordinated unsecured debentures, notes
and/or other evidences of indebtedness in one or more series, to be issued under
a Subordinated Indenture (the "Subordinated Indenture") that is expected to be
entered into between the Company and U.S. Bank Trust National Association, as
trustee, and junior subordinated debentures, to be issued under a Junior
Subordinated Indenture (the "Junior Subordinated Indenture") dated as of
December 15, 1996 between the Company and The First National Bank of Chicago, as
trustee, (iii) shares of preferred stock of the Company, no par value (the
"Preferred Stock"), to be issued in one or more series and (iv) unconditional
and irrevocable guarantees (the "Guarantees" and each a "Guarantee") of certain
payments and obligations of each of the Issuer Trusts (as defined herein) to be
issued by the Company under one or more Guarantee Agreements (the "Guarantee
Agreements" and each a "Guarantee Agreement") that are expected to be entered
into between the Company and The First National Bank of Chicago, as debenture
trustee, with respect to Capital Securities proposed to be issued by each such
Issuer Trust; and (b) the proposed issue by State Street Capital Trust I, State
Street Capital Trust II and State Street Capital Trust III, each a Delaware
business trust (each, an "Issuer Trust" and together, the "Issuer Trusts"), of
up to $350,000,000 aggregate amount of preferred securities representing
beneficial ownership interests in such Issuer Trusts (the "Capital Securities").
The Debt Securities, the Preferred Stock, the Guarantees and the Capital
Securities are referred to herein collectively as the "Securities".

     We have acted as counsel for the Company and each of the Issuer Trusts in
connection with the proposed issue and sale of the Securities.  We are familiar
with the proceedings taken by the Company and each Issuer Trust in respect
thereof and have examined originals or certified or attested copies of such
certificates, records and documents as we have deemed necessary for the purposes
of this opinion.  We have assumed the genuineness and authenticity of all
documents submitted to us as originals and the conformity to originals of all
documents submitted to us as copies.

     We express no opinion as to the laws of any jurisdiction other than those
of the Commonwealth of Massachusetts, the Delaware General Corporation Law and
the federal laws of the United States of America.

     For purposes of this opinion, we have examined and relied upon the
information set forth in the Registration Statement (as defined herein) and such
other documents and records that we have deemed necessary.

     Based on and subject to the foregoing, we are of the opinion that:

 
State Street Corporation
State Street Capital Trust I
State Street Capital Trust II
State Street Capital Trust III           -3-                      April 1, 1998


     1.    When the Registration Statement (the "Registration Statement")
relating to the Securities filed with the Securities and Exchange Commission
under the Securities Act of 1933, as amended (the "Act") has become effective
under the Act, the terms of the Debt Securities and of their issuance and sale
have been duly established in conformity with the applicable Indenture, and the
Debt Securities have been duly executed and authenticated in accordance with the
applicable Indenture and issued and sold as contemplated in the Registration
Statement, the Debt Securities will constitute valid and legally binding
obligations of the Company, subject to (i) bankruptcy, insolvency,
reorganization, moratorium and other laws of general application affecting the
rights and remedies of creditors and (ii) general principles of equity,
regardless of whether applied in a proceeding in equity or at law.

     2.    When the Registration Statement has become effective under the Act,
the terms of the Preferred Stock of a particular series and of its issuance and
sale have been duly established in conformity with the Company's Articles of
Organization, a certificate of designation, preferences and rights with respect
to the Preferred Stock of such series has been duly filed with the Secretary of
State of the Commonwealth of Massachusetts, and the Preferred Stock of such
series has been duly issued and sold as contemplated in the Registration
Statement, the Preferred Stock of such series will be validly issued, fully
paid, and nonassessable.

     3.  When the Registration Statement has become effective under the Act, the
terms of each Guarantee and of its issuance have been duly established in
conformity with the applicable Guarantee Agreement and such Guarantee has been
duly executed and authenticated in accordance with the applicable Guarantee
Agreement and issued as contemplated in the Registration Statement, each
Guarantee will constitute a valid and legally binding obligation of the Company,
subject to (i) bankruptcy, insolvency, reorganization, moratorium and other laws
of general application affecting the rights and remedies of creditors and (ii)
general principles of equity, regardless of whether applied in a proceeding in
equity or at law.

     We understand that this opinion is to be used in connection with the
Registration Statement.  We consent to the filing of this opinion with and as
part of said Registration Statement and the use of our name therein and in the
related Prospectus under the caption "Validity of Securities".

                              Very truly yours,

                              /s/ Ropes & Gray 

                              Ropes & Gray