Exhibit 5





                                         , 1997


S&T Bancorp, Inc.
800 Philadelphia Street
Indiana, PA 15701


Ladies and Gentlemen:

     Reference is made to the Registration Statement on Form S-4 ("Registration 
Statement") of S&T Bancorp, Inc., a Pennsylvania corporation ("S&T"), with 
respect to 3,036,075 shares of $2.50 par value common stock of S&T ("S&T Common 
Stock") that may be issued in connection with the proposed transaction pursuant 
to which Peoples Bank of Unity ("Peoples") will be merged (the "Merger") with 
and into S&T's wholly-owned subsidiary, S&T Bank.

     The Merger is to be effected pursuant to an Agreement and Plan of 
Reorganization, dated as of November 25, 1996, and a related Agreement and Plan 
of Merger (collectively, the "Agreement") between S&T and Peoples and joined in 
by S&T Bank, pursuant to which each share of the $10.00 par value common stock 
of Peoples ("Peoples Common Stock") outstanding immediately prior to the 
effective time of the Merger (other than shares held by dissenting shareholders)
will be converted into 26.25 shares of S&T Common Stock, with cash being paid in
lieu of the issuance of fractional shares.

     We have been requested to furnish an opinion to be included as Exhibit 5 to
the Registration Statement. In conjunction with the furnishing of this opinion, 
we have examined such corporate documents and have made such investigation of 
matters of fact and law as we have deemed necessary to render this opinion. Our 
opinion is based on our review of the latest standard compilation available to 
us of the Pennsylvania Business Corporation Law of 1988.

     Based upon such examination and investigation and upon the assumption that 
there will be no material changes in the documents we examined and the matters 
investigated, we are of the opinion that the shares of S&T Common Stock included
in the Registration Statement that may be issued to the holders of Peoples 
Common Stock in connection with the Merger have been duly authorized by S&T and 
that, when issued to such shareholders in accordance with the terms of the 
Agreement upon consummation of the Merger, such shares of S&T Common Stock will 
be validly issued, fully paid, and nonassessable under the Pennsylvania Business
Corporation Law of 1988 as in effect on this date.

     We consent to the filing of this opinion as an exhibit to the Registration 
Statement and to the reference to us under the caption "Legal Opinion" in the 
Proxy Statement/Prospectus included therein. In giving the foregoing consent, we
do not thereby admit that we are in the category of persons whose consent is 
required under Section 7 of the Securities Act of 1933, as amended, or the rules
and regulations of the Securities and Exchange Commission thereunder.

                                       Sincerely,