<PAGE>   1

       AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 8, 2000
                                                     REGISTRATION NO. 333-_____
-------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                 ---------------

                                    FORM S-8
             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
                                 ---------------

                              GLACIER BANCORP, INC.
             (Exact name of registrant as specified in its charter)

              DELAWARE                                   81-0519541
  (State or other jurisdiction of               (I.R.S. employer identification
   incorporation or organization)                           no.)

          P.O. BOX 27, 49 COMMONS LOOP, KALISPELL, MONTANA 59903-0027
                                 406) 756-4200
               (Address, including zip code, and telephone number,
                 including area code, of registrant's principal
                               executive offices)
                                 ---------------


                  MOUNTAIN WEST BANK RESTATED STOCK OPTION PLAN
                              (Full title of plan)

                                 ---------------

                          Copies of communications to:

STEPHEN M. KLEIN, ESQ.                          MICHAEL J. BLODNICK
Graham & Dunn P.C.                              P. O. Box 27
1420 Fifth Avenue, 33rd Floor                   49 Commons Loop
Seattle, Washington  98101                      Kalispell,  Montana  59903-0027
(206) 340-9648                                  (406) 756-4200

<TABLE>
<CAPTION>
                                   CALCULATION OF REGISTRATION FEE
          ---------------------------------------------------------------------------------------------
                                                                      Proposed
                                                   Proposed maximum   maximum
          Title of              Amount             offering           aggregate          Amount of
          securities to be      to be              price              offering           registration
          registered            registered         per share (1)      price (1)          fee
          ----------            -----------        -------------      ---------          ------------
          <S>                   <C>                <C>                <C>                <C>
          Common shares, $.01    (2)135,731        $14.69             $1,993,888         $526.39
          par value
          ---------------------------------------------------------------------------------------------
</TABLE>

Notes:
    1.  Estimated solely for the purpose of calculating the amount of the
        registration fee. Pursuant to Rule 457(c) under the Securities Act of
        1933, as amended ("Securities Act"), the price per share is estimated to
        be $14.69 based upon the average of the high ($15.25) and the low
        ($14.125) trading prices of the common stock, $.01 par value per share
        ("Common Stock") of Glacier Bancorp, Inc. (the "Registrant") as reported
        on the Nasdaq Stock Market on May 4, 2000.

    2.  Shares of Registrant's Common Stock issuable upon exercise of options
        outstanding under the Mountain West Bank Restated Stock Option Plan (the
        "Plan"), together with an indeterminate number of additional shares
        which may be necessary to adjust the number of shares reserved for
        issuance under the Plan as a result of any future stock split, stock
        dividend or similar adjustment of the outstanding Common Stock, as
        provided in Rule 416(a) under the Securities Act.


<PAGE>   2



             PART II. INFORMATION REQUIRED IN REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

        The documents listed below are incorporated by reference in the
Registration Statement. In addition, all documents subsequently filed by
Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities
Exchange Act of 1934, as amended ("Exchange Act") prior to Registrant's filing
of a post-effective amendment which indicates that all securities offered have
been sold or which deregisters all securities then remaining unsold, shall be
deemed to be incorporated by reference into this Registration Statement and to
be a part hereof from the date of filing of such documents.

        (a) The Registrant's Annual Report on Form 10-K for the fiscal year
ended December 31, 1999, filed pursuant to Section 13(a) or 15(d) of the
Exchange Act, which contains audited financial statements for the most recent
fiscal year for which such statements have been filed.

        (b) All other reports filed pursuant to Section 13(a) or 15(d) of the
Exchange Act since the end of the fiscal year covered by the Annual Report on
Form 10-K referred to in (a) above.

        (c) The description of the Common Shares contained in the Proxy
Statement/Prospectus dated December 17, 1999 and included in the Registration
Statement on Form S-4 (Registration No. 333-90701) filed by Bancorp on November
10, 1999, including any amendments or reports filed for the purpose of updating
such description.

ITEM 4.  DESCRIPTION OF SECURITIES.

        Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

        The validity of the shares offered pursuant to the Plan will be passed
upon by Graham & Dunn, PC, 1420 Fifth Avenue, 33rd Floor, Seattle, Washington
98101.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        Section 145 of the DGCL provides that a corporation may indemnify
directors and officers as well as other employees and individuals against
expenses (including attorneys' fees), judgments, fines and amounts paid in
settlement in connection with specified actions, suits or proceedings, whether
civil, criminal, administrative or investigative (other than an action by or in
the right of the corporation--a "derivative action"), if they acted in good
faith and in a manner they reasonably believed to be in, or not opposed to, the
best interests of the corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe their conduct was unlawful. A
similar standard is applicable in the case of derivative actions, except that
indemnification only extends to expenses (including attorneys' fees) incurred in
connection with the defense or settlement of such actions, and the statute
requires court approval before there can be any



                                       1
<PAGE>   3

indemnification where the person seeking indemnification has been found liable
to the corporation. The statute provides that it is not exclusive of other
indemnification that may be granted by a corporation's charter, bylaws,
disinterested director vote, stockholder vote, agreement or otherwise.

        Article VI of Glacier Bancorp, Inc.'s ("Glacier") Bylaws requires the
indemnification of any person made or threatened to be made party to any
threatened, pending or completed action, suit or proceeding, whether civil,
criminal, administrative or investigative, by reason of the fact that such
person is or was a director, officer or employee of the Registrant or any
predecessor of the Registrant, or is or was serving at the request of the
Registrant or any predecessor of the Registrant as a director, officer or
employee of another corporation, partnership, joint venture, trust or other
enterprise, against expenses (including attorneys' fees), judgments, fines,
excise taxes and amounts paid in settlement in connection with such action, suit
or proceeding to the fullest extent authorized under Section 145 of the DGCL;
provided however, that the Registrant will not be liable for any amounts due in
connection with a settlement of any action, suit or proceeding effected without
the Registrant's prior written consent, or any action, suit or proceeding
initiated by any person seeking indemnification pursuant to the Bylaws without
the prior written consent of the Registrant.

        Section 102(b)(7) of the DGCL permits a corporation to provide in its
certificate of incorporation that a director of the corporation shall not be
personally liable to the corporation or its stockholders for monetary damages
for breach of fiduciary duty as a director, except for liability for (i) any
breach of the director's duty of loyalty to the corporation or its stockholders,
(ii) acts or omissions not in good faith or which involve intentional misconduct
or a knowing violation of law, (iii) payments of unlawful dividends or unlawful
stock repurchases or redemptions, or (iv) any transaction from which the
director derived an improper personal benefit.

        Article 8 of Glacier's Certificate of Incorporation provides that the
personal liability of the Registrant's directors and officers for monetary
damages shall be eliminated to the fullest extent permitted by the DGCL as it
exists or may thereafter be in effect. Any amendment to, modification or repeal
of such Article 8 shall not adversely affect the rights provided thereby with
respect to any claim, issue or matter in any proceeding that is based in any
respect on any alleged action or failure to act prior to any such amendment,
modification or repeal.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

        Not applicable.




                                       2
<PAGE>   4

ITEM 8.  EXHIBITS.
<TABLE>
<CAPTION>
 Exhibit Number                             Description
 -------------                              ------------
 <S>                     <C>
       5.1               Opinion of Graham & Dunn, P.C., Registrant's legal counsel, regarding
                         legality of the Common Stock being registered.
      23.1               Consent of Graham & Dunn (included in Exhibit 5.1).
      23.2               Consent of KPMG LLP.
      24.1               Powers of Attorney (see the Signature Page and certified resolutions
                         of the Registrant's Board of Directors).
      99.1               Mountain West Bank Restated Stock Option Plan.
      99.2               Plan and Agreement and Merger among Registrant, Mountain West Bank and
                         New Mountain West Bank, dated as of September 9, 1999(1).
</TABLE>
------------------
(1) Incorporated by referenced from Exhibit 2.1, to Registrant's Registration
Statement on Form S-4 (Registration No. 333-90701)

ITEM 9.  UNDERTAKINGS.

A.      The undersigned Registrant hereby undertakes:

        (1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this Registration Statement:

                (i)   To include any prospectus required by Section 10(a)(3)
of the Securities Act;

                (ii) To reflect in the prospectus any facts or events arising
after the effective date of the Registration Statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the Registration
Statement. Notwithstanding the foregoing, any increase or decrease in volume of
securities offered (if the total dollar value of securities offered would not
exceed that which was registered) and any deviation from the low or high end of
the estimated maximum offering range may be reflected in the form of prospectus
filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
changes in volume and price represent no more than a 20% change in the maximum
aggregate offering price set forth in the "Calculation of Registration Fee"
table in the effective Registration Statement;

                (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the Registration Statement or
any material change to such information in the Registration Statement;



                                       3
<PAGE>   5

      Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) of this
section do not apply if the Registration Statement is on Form S-3, Form S-8 or
Form F-3, and the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed with or
furnished to the Commission by the Registrant pursuant to Section 13 or Section
15(d) of the Securities Exchange Act that are incorporated by reference in the
Registration Statement.

      (2) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

      (3) To remove from registration by means of a post-effective amendment any
of the securities being registered which remain unsold at the termination of the
offering.

      B. The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in the Registration Statement shall be deemed to be a
new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

      C. Insofar as indemnification for liabilities arising under the Securities
Act may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Act and is, therefore, unenforceable.
In the event that a claim for indemnification against such liabilities (other
than the payment by the Registrant of expenses incurred or paid by a director,
officer of controlling person of the Registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the Registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.




                                       4
<PAGE>   6

                                   SIGNATURES

        Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Kalispell, State of Montana, on the 26th day of
April, 2000.

                               GLACIER BANCORP, INC.


                                   By  /s/ Michael J. Blodnick
                                     -------------------------
                                       Michael J. Blodnick
                                       President and Chief Executive Officer

                                POWER OF ATTORNEY

        Each person whose individual signature appears below hereby authorizes
and appoints Michael J. Blodnick and James H. Strosahl, and each of them, with
full power of substitution and full power to act without the other, as his true
and lawful attorney-in-fact and agent to act in his name, place and stead, and
to execute in the name and on behalf of each person, individually and in each
capacity stated below, and to file any and all amendments to this Registration
Statement, including any and all post-effective amendments.

        Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities indicated,
on the 26th day of April, 2000.

<TABLE>
<CAPTION>
    Signature                                      Title
    ---------                                      -----
<S>                                             <C>
   /s/ Michael J. Blodnick                      President, Chief Executive Officer and Director
------------------------------------            (Principal Executive Officer)
Michael J. Blodnick


  /s/  James H. Strosahl                        Executive Vice President and CFO
------------------------------------            (Principal Financial and Accounting Officer)
James H. Strosahl


  /s/ John S. MacMillan                           Chairman of the Board
------------------------------------
John S. MacMillan
</TABLE>




                                       5
<PAGE>   7


<TABLE>
<S>                                               <C>
                                                  Director
------------------------------------
William L. Bouchee

                                                  Director
------------------------------------
Allen J. Fetscher

  /s/ Fred J. Flanders                            Director
------------------------------------
Fred J. Flanders

  /s/ Jon W. Hippler                              Director
------------------------------------
Jon W. Hippler

                                                  Director
------------------------------------
L. Peter Larson

  /s/ F. Charles Mercord                          Director
------------------------------------
F. Charles Mercord

  /s/ Everit A. Sliter                            Director
------------------------------------
Everit A. Sliter

  /s/ Harold A. Tutvedt                           Director
------------------------------------
Harold A. Tutvedt

</TABLE>



                                       6
<PAGE>   8

                                INDEX OF EXHIBITS
<TABLE>
<CAPTION>
 Exhibit Number                        Description
 --------------                        -----------
<S>                      <C>
       5.1               Opinion of Graham & Dunn, P.C., Registrant's legal counsel, regarding
                         legality of the Common Stock being registered.
      23.1               Consent of Graham & Dunn (included in Exhibit 5.1).
      23.2               Consent of KPMG LLP.
      24.1               Powers of Attorney (see the Signature Page and certified resolutions
                         of the Registrant's Board of Directors).
      99.1               Mountain West Bank Restated Stock Option Plan.
      99.2               Plan and Agreement and Merger among Registrant, Mountain West Bank and
                         New Mountain West Bank, dated as of September 9, 1999(1).
</TABLE>

------------------
(1) Incorporated by referenced from Exhibit 2.1, to Registrant's Registration
Statement on Form S-4 (Registration No. 333-90701)


                                       7
[{"type": "S-8", "sequence": "1", "description": "FORM S-8", "secsgml_size_bytes": 19446}]
{"company-data": {"conformed-name": "GLACIER BANCORP INC", "cik": "0000868671", "assigned-sic": "6035", "irs-number": "810468393", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-36514", "film-number": "621786"}, "business-address": {"street1": "PO BOX 27", "street2": "49 COMMONS LOOP", "city": "KALISPELL", "state": "MT", "zip": "59901", "phone": "4067564200"}, "mail-address": {"street1": "PO BOX 27", "street2": "202 MAIN STREET", "city": "49 COMMONS LOOP", "state": "MT", "zip": "59901"}}
1

       AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON MAY 8, 2000
                                                     REGISTRATION NO. 333-_____
-------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                                 ---------------

                                    FORM S-8
             REGISTRATION STATEMENT UNDER THE SECURITIES ACT OF 1933
                                 ---------------

                              GLACIER BANCORP, INC.
             (Exact name of registrant as specified in its charter)

              DELAWARE                                   81-0519541
  (State or other jurisdiction of               (I.R.S. employer identification
   incorporation or organization)                           no.)

          P.O. BOX 27, 49 COMMONS LOOP, KALISPELL, MONTANA 59903-0027
                                 406) 756-4200
               (Address, including zip code, and telephone number,
                 including area code, of registrant's principal
                               executive offices)
                                 ---------------

                  MOUNTAIN WEST BANK RESTATED STOCK OPTION PLAN
                              (Full title of plan)

                                 ---------------

                          Copies of communications to:

STEPHEN M. KLEIN, ESQ.                          MICHAEL J. BLODNICK
Graham & Dunn P.C.                              P. O. Box 27
1420 Fifth Avenue, 33rd Floor                   49 Commons Loop
Seattle, Washington  98101                      Kalispell,  Montana  59903-0027
(206) 340-9648                                  (406) 756-4200
CALCULATION OF REGISTRATION FEE
          ---------------------------------------------------------------------------------------------
                                                                      Proposed
                                                   Proposed maximum   maximum
          Title of              Amount             offering           aggregate          Amount of
          securities to be      to be              price              offering           registration
          registered            registered         per share (1)      price (1)          fee
          ----------            -----------        -------------      ---------          ------------
Common shares, $.01    (2)135,731        $14.69             $1,993,888         $526.39
          par value
          ---------------------------------------------------------------------------------------------
Notes:
    1.  Estimated solely for the purpose of calculating the amount of the
        registration fee. Pursuant to Rule 457(c) under the Securities Act of
        1933, as amended ("Securities Act"), the price per share is estimated to
        be $14.69 based upon the average of the high ($15.25) and the low
        ($14.125) trading prices of the common stock, $.01 par value per share
        ("Common Stock") of Glacier Bancorp, Inc. (the "Registrant") as reported
        on the Nasdaq Stock Market on May 4, 2000.

    2.  Shares of Registrant's Common Stock issuable upon exercise of options
        outstanding under the Mountain West Bank Restated Stock Option Plan (the
        "Plan"), together with an indeterminate number of additional shares
        which may be necessary to adjust the number of shares reserved for
        issuance under the Plan as a result of any future stock split, stock
        dividend or similar adjustment of the outstanding Common Stock, as
        provided in Rule 416(a) under the Securities Act.
2

             PART II. INFORMATION REQUIRED IN REGISTRATION STATEMENT

ITEM 3.  INCORPORATION OF DOCUMENTS BY REFERENCE.

        The documents listed below are incorporated by reference in the
Registration Statement. In addition, all documents subsequently filed by
Registrant pursuant to Sections 13(a), 13(c), 14 and 15(d) of the Securities
Exchange Act of 1934, as amended ("Exchange Act") prior to Registrant's filing
of a post-effective amendment which indicates that all securities offered have
been sold or which deregisters all securities then remaining unsold, shall be
deemed to be incorporated by reference into this Registration Statement and to
be a part hereof from the date of filing of such documents.

        (a) The Registrant's Annual Report on Form 10-K for the fiscal year
ended December 31, 1999, filed pursuant to Section 13(a) or 15(d) of the
Exchange Act, which contains audited financial statements for the most recent
fiscal year for which such statements have been filed.

        (b) All other reports filed pursuant to Section 13(a) or 15(d) of the
Exchange Act since the end of the fiscal year covered by the Annual Report on
Form 10-K referred to in (a) above.

        (c) The description of the Common Shares contained in the Proxy
Statement/Prospectus dated December 17, 1999 and included in the Registration
Statement on Form S-4 (Registration No. 333-90701) filed by Bancorp on November
10, 1999, including any amendments or reports filed for the purpose of updating
such description.

ITEM 4.  DESCRIPTION OF SECURITIES.

        Not applicable.

ITEM 5.  INTERESTS OF NAMED EXPERTS AND COUNSEL.

        The validity of the shares offered pursuant to the Plan will be passed
upon by Graham & Dunn, PC, 1420 Fifth Avenue, 33rd Floor, Seattle, Washington
98101.

ITEM 6.  INDEMNIFICATION OF DIRECTORS AND OFFICERS.

        Section 145 of the DGCL provides that a corporation may indemnify
directors and officers as well as other employees and individuals against
expenses (including attorneys' fees), judgments, fines and amounts paid in
settlement in connection with specified actions, suits or proceedings, whether
civil, criminal, administrative or investigative (other than an action by or in
the right of the corporation--a "derivative action"), if they acted in good
faith and in a manner they reasonably believed to be in, or not opposed to, the
best interests of the corporation, and, with respect to any criminal action or
proceeding, had no reasonable cause to believe their conduct was unlawful. A
similar standard is applicable in the case of derivative actions, except that
indemnification only extends to expenses (including attorneys' fees) incurred in
connection with the defense or settlement of such actions, and the statute
requires court approval before there can be any

                                       1
3

indemnification where the person seeking indemnification has been found liable
to the corporation. The statute provides that it is not exclusive of other
indemnification that may be granted by a corporation's charter, bylaws,
disinterested director vote, stockholder vote, agreement or otherwise.

        Article VI of Glacier Bancorp, Inc.'s ("Glacier") Bylaws requires the
indemnification of any person made or threatened to be made party to any
threatened, pending or completed action, suit or proceeding, whether civil,
criminal, administrative or investigative, by reason of the fact that such
person is or was a director, officer or employee of the Registrant or any
predecessor of the Registrant, or is or was serving at the request of the
Registrant or any predecessor of the Registrant as a director, officer or
employee of another corporation, partnership, joint venture, trust or other
enterprise, against expenses (including attorneys' fees), judgments, fines,
excise taxes and amounts paid in settlement in connection with such action, suit
or proceeding to the fullest extent authorized under Section 145 of the DGCL;
provided however, that the Registrant will not be liable for any amounts due in
connection with a settlement of any action, suit or proceeding effected without
the Registrant's prior written consent, or any action, suit or proceeding
initiated by any person seeking indemnification pursuant to the Bylaws without
the prior written consent of the Registrant.

        Section 102(b)(7) of the DGCL permits a corporation to provide in its
certificate of incorporation that a director of the corporation shall not be
personally liable to the corporation or its stockholders for monetary damages
for breach of fiduciary duty as a director, except for liability for (i) any
breach of the director's duty of loyalty to the corporation or its stockholders,
(ii) acts or omissions not in good faith or which involve intentional misconduct
or a knowing violation of law, (iii) payments of unlawful dividends or unlawful
stock repurchases or redemptions, or (iv) any transaction from which the
director derived an improper personal benefit.

        Article 8 of Glacier's Certificate of Incorporation provides that the
personal liability of the Registrant's directors and officers for monetary
damages shall be eliminated to the fullest extent permitted by the DGCL as it
exists or may thereafter be in effect. Any amendment to, modification or repeal
of such Article 8 shall not adversely affect the rights provided thereby with
respect to any claim, issue or matter in any proceeding that is based in any
respect on any alleged action or failure to act prior to any such amendment,
modification or repeal.

ITEM 7.  EXEMPTION FROM REGISTRATION CLAIMED.

        Not applicable.

                                       2
4

ITEM 8.  EXHIBITS.
Exhibit Number                             Description
 -------------                              ------------
5.1               Opinion of Graham & Dunn, P.C., Registrant's legal counsel, regarding
                         legality of the Common Stock being registered.
      23.1               Consent of Graham & Dunn (included in Exhibit 5.1).
      23.2               Consent of KPMG LLP.
      24.1               Powers of Attorney (see the Signature Page and certified resolutions
                         of the Registrant's Board of Directors).
      99.1               Mountain West Bank Restated Stock Option Plan.
      99.2               Plan and Agreement and Merger among Registrant, Mountain West Bank and
                         New Mountain West Bank, dated as of September 9, 1999(1).
------------------
(1) Incorporated by referenced from Exhibit 2.1, to Registrant's Registration
Statement on Form S-4 (Registration No. 333-90701)

ITEM 9.  UNDERTAKINGS.

A.      The undersigned Registrant hereby undertakes:

        (1) To file, during any period in which offers or sales are being made,
a post-effective amendment to this Registration Statement:

                (i)   To include any prospectus required by Section 10(a)(3)
of the Securities Act;

                (ii) To reflect in the prospectus any facts or events arising
after the effective date of the Registration Statement (or the most recent
post-effective amendment thereof) which, individually or in the aggregate,
represent a fundamental change in the information set forth in the Registration
Statement. Notwithstanding the foregoing, any increase or decrease in volume of
securities offered (if the total dollar value of securities offered would not
exceed that which was registered) and any deviation from the low or high end of
the estimated maximum offering range may be reflected in the form of prospectus
filed with the Commission pursuant to Rule 424(b) if, in the aggregate, the
changes in volume and price represent no more than a 20% change in the maximum
aggregate offering price set forth in the "Calculation of Registration Fee"
table in the effective Registration Statement;

                (iii) To include any material information with respect to the
plan of distribution not previously disclosed in the Registration Statement or
any material change to such information in the Registration Statement;

                                       3
5

      Provided, however, that paragraphs (a)(1)(i) and (a)(1)(ii) of this
section do not apply if the Registration Statement is on Form S-3, Form S-8 or
Form F-3, and the information required to be included in a post-effective
amendment by those paragraphs is contained in periodic reports filed with or
furnished to the Commission by the Registrant pursuant to Section 13 or Section
15(d) of the Securities Exchange Act that are incorporated by reference in the
Registration Statement.

      (2) That, for the purpose of determining any liability under the
Securities Act, each such post-effective amendment shall be deemed to be a new
registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

      (3) To remove from registration by means of a post-effective amendment any
of the securities being registered which remain unsold at the termination of the
offering.

      B. The undersigned Registrant hereby undertakes that, for purposes of
determining any liability under the Securities Act, each filing of the
Registrant's annual report pursuant to Section 13(a) or Section 15(d) of the
Exchange Act (and, where applicable, each filing of an employee benefit plan's
annual report pursuant to Section 15(d) of the Exchange Act) that is
incorporated by reference in the Registration Statement shall be deemed to be a
new registration statement relating to the securities offered therein, and the
offering of such securities at that time shall be deemed to be the initial bona
fide offering thereof.

      C. Insofar as indemnification for liabilities arising under the Securities
Act may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions, or otherwise, the Registrant
has been advised that in the opinion of the Commission such indemnification is
against public policy as expressed in the Act and is, therefore, unenforceable.
In the event that a claim for indemnification against such liabilities (other
than the payment by the Registrant of expenses incurred or paid by a director,
officer of controlling person of the Registrant in the successful defense of any
action, suit or proceeding) is asserted by such director, officer or controlling
person in connection with the securities being registered, the Registrant will,
unless in the opinion of its counsel the matter has been settled by controlling
precedent, submit to a court of appropriate jurisdiction the question whether
such indemnification by it is against public policy as expressed in the Act and
will be governed by the final adjudication of such issue.

                                       4
6

                                   SIGNATURES

        Pursuant to the requirements of the Securities Act, the Registrant
certifies that it has reasonable grounds to believe that it meets all of the
requirements for filing on Form S-8 and has duly caused this Registration
Statement to be signed on its behalf by the undersigned, thereunto duly
authorized, in the City of Kalispell, State of Montana, on the 26th day of
April, 2000.

                               GLACIER BANCORP, INC.

                                   By  /s/ Michael J. Blodnick
                                     -------------------------
                                       Michael J. Blodnick
                                       President and Chief Executive Officer

                                POWER OF ATTORNEY

        Each person whose individual signature appears below hereby authorizes
and appoints Michael J. Blodnick and James H. Strosahl, and each of them, with
full power of substitution and full power to act without the other, as his true
and lawful attorney-in-fact and agent to act in his name, place and stead, and
to execute in the name and on behalf of each person, individually and in each
capacity stated below, and to file any and all amendments to this Registration
Statement, including any and all post-effective amendments.

        Pursuant to the requirements of the Securities Act, this Registration
Statement has been signed by the following persons in the capacities indicated,
on the 26th day of April, 2000.
Signature                                      Title
    ---------                                      -----
/s/ Michael J. Blodnick                      President, Chief Executive Officer and Director
------------------------------------            (Principal Executive Officer)
Michael J. Blodnick

  /s/  James H. Strosahl                        Executive Vice President and CFO
------------------------------------            (Principal Financial and Accounting Officer)
James H. Strosahl

  /s/ John S. MacMillan                           Chairman of the Board
------------------------------------
John S. MacMillan
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Director
------------------------------------
William L. Bouchee

                                                  Director
------------------------------------
Allen J. Fetscher

  /s/ Fred J. Flanders                            Director
------------------------------------
Fred J. Flanders

  /s/ Jon W. Hippler                              Director
------------------------------------
Jon W. Hippler

                                                  Director
------------------------------------
L. Peter Larson

  /s/ F. Charles Mercord                          Director
------------------------------------
F. Charles Mercord

  /s/ Everit A. Sliter                            Director
------------------------------------
Everit A. Sliter

  /s/ Harold A. Tutvedt                           Director
------------------------------------
Harold A. Tutvedt
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                                INDEX OF EXHIBITS
Exhibit Number                        Description
 --------------                        -----------
5.1               Opinion of Graham & Dunn, P.C., Registrant's legal counsel, regarding
                         legality of the Common Stock being registered.
      23.1               Consent of Graham & Dunn (included in Exhibit 5.1).
      23.2               Consent of KPMG LLP.
      24.1               Powers of Attorney (see the Signature Page and certified resolutions
                         of the Registrant's Board of Directors).
      99.1               Mountain West Bank Restated Stock Option Plan.
      99.2               Plan and Agreement and Merger among Registrant, Mountain West Bank and
                         New Mountain West Bank, dated as of September 9, 1999(1).
------------------
(1) Incorporated by referenced from Exhibit 2.1, to Registrant's Registration
Statement on Form S-4 (Registration No. 333-90701)

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