<PAGE>


                                                                    EXHIBIT 10.1

                                VOTING AGREEMENT

     This Voting Agreement ("Voting Agreement"), dated as of February 6, 2009,
is among Glacier Bancorp, Inc., ("GBCI"), First Company, First National Bank &
Trust (the "Bank"), and the undersigned, each of whom is a director of First
Company or the Bank and/or a principal shareholder of First Company (in either
case, a "Shareholder"). This Voting Agreement will be effective upon the signing
of the Merger Agreement (defined below).

                                     RECITAL

     As an inducement for GBCI, First Company and the Bank to enter into the
Plan and Agreement of Merger (the "Merger Agreement") dated as of the date
hereof, whereby, among other things, First Company will merge with and into
GBCI, and the Bank will become a wholly owned subsidiary of GBCI (the "Merger"),
each of the Shareholders, for such Shareholder and his, her or its heirs and
legal representatives, hereby agrees as follows:

                                    AGREEMENT

1.   VOTING AND OTHER MATTERS. Each Shareholder will vote or cause to be voted
     all shares of First Company common stock that such Shareholder beneficially
     owns, with power to vote or direct the voting of (the "Shares"), in favor
     of approval of the Merger Agreement and the Merger. In addition, each
     Shareholder who is a director of First Company ("Director") will (a)
     recommend to the shareholders of First Company that they approve the Merger
     Agreement, and (b) refrain from any actions or omissions inconsistent with
     the foregoing, except as otherwise required by law, including, without
     limitation, the Directors' fiduciary duties to First Company and its
     shareholders.

2.   NO TRANSFER. Until the earlier of the consummation of the Merger or the
     termination of the Merger Agreement, no Shareholder may sell, transfer,
     permit a lien or other encumbrance to be created with respect to, or grant
     any proxy in respect of (except for proxies solicited by the board of
     directors of First Company in connection with the First Company
     shareholders' meeting at which the Merger is presented for shareholder
     approval) any Shares, unless all other parties to any such sale or other
     transaction enter into an agreement in form and substance satisfactory to
     GBCI embodying the benefits and rights contained in this Voting Agreement.

3.   INDIVIDUAL OBLIGATIONS. Obligations of each Shareholder under this Voting
     Agreement are intended to be several and not joint.

4.   MISCELLANEOUS.

     a.   Severability. If any provision of this Voting Agreement or the
          application of such provision to any person or circumstances will be
          held invalid or unenforceable by a court of competent jurisdiction,
          such provision or application will be unenforceable only to the extent
          of such invalidity or unenforceability, and the remainder of the
          provision held invalid or unenforceable and the application of

<PAGE>

          such provision to persons or circumstances, other than the party as to
          which it is held invalid, and the remainder of this Voting Agreement,
          will not be affected.

     b.   Counterparts. This Voting Agreement may be executed in one or more
          counterparts, including facsimile counterparts, each of which will be
          deemed an original, but all of which taken together will constitute
          one and the same document.

     c.   Governing Law. This Voting Agreement will be deemed a contract made
          under, and for all purposes will be construed in accordance with, the
          laws of the State of Wyoming. Venue of any legal action or proceeding
          between the parties related to this Voting Agreement shall be in
          Yellowstone County, Montana, and the parties each consent to the
          personal jurisdiction of the courts of the State of Montana and the
          federal courts located in Montana. Each Shareholder agrees not to
          claim that Yellowstone County, Montana, is an inconvenient place for
          trial.

     e.   Remedies. Any breach of this Voting Agreement entitles GBCI and First
          Company to injunctive relief and/or specific performance, as well as
          any other legal or equitable remedies to which GBCI may be entitled.

     f.   Defined Terms. Unless otherwise defined herein, capitalized terms used
          in this Voting Agreement have the meaning assigned to them in the
          Merger Agreement.

     g.   Termination of Agreement. The Voting Agreement shall be effective from
          the date hereof and shall terminate and be of no further force and
          effect upon the earlier of (i) the Effective Time; or (ii) the
          termination of the Merger Agreement in accordance with its terms.

                      SIGNATURES APPEAR ON FOLLOWING PAGE.


                                       2

<PAGE>

This Voting Agreement is signed as of February 6, 2009.

GLACIER BANCORP, INC.                   FIRST COMPANY


By                                      By
   ----------------------------------      -------------------------------------
   Michael J. Blodnick
   President & Chief Executive
   Officer


                                        FIRST NATIONAL BANK & TRUST


                                        By
                                           -------------------------------------

SHAREHOLDERS:


-------------------------------------   ----------------------------------------
Bradley D. Bonner                       David R. Reetz


-------------------------------------   ----------------------------------------
Gary L. Mills                           Joel Revill


-------------------------------------   ----------------------------------------
Richard S. Nelson                       Victor J. Riley, Jr.


-------------------------------------   ----------------------------------------
Richard T. Nelson                       Colin M. Simpson


-------------------------------------   ----------------------------------------
Robert A. Nelson                        Julie M. Sullivan


-------------------------------------   ----------------------------------------
Douglas V. Nissen                       Jack T. Turnell


                                        3