CONFIRMING STATEMENT


This Statement confirms that the undersigned, Michelle Petrovsky,
has authorized and designated each of Robert E. Rout, Wendy S. Bell or
Timothy P. McKee to execute and file on the undersigned's behalf all
Forms 3, 4 and 5 (including any amendments thereto) that the
undersigned may be required to file with the U.S. Securities and
Exchange Commission as a result of the undersigned's ownership
of or transactions in securities of S&T Bancorp, Inc.  The authority of
Robert E. Rout, Wendy S. Bell or Timothy P. McKee under this Statement
shall continue until the undersigned is no longer required to file Forms
3, 4 and 5 with regard to his/her ownership of or transactions in securities
of S&T Bancorp, Inc., unless earlier revoked in writing.  The undersigned
acknowledges that Robert E. Rout, Wendy S. Bell or Timothy P. McKee
are not assuming any of the undersigned's responsibilities to comply
with Section 16 of the Securities Exchange Act of 1934.


/s/ Michelle Petrovsky

_________________________


Date:  January 2, 2008