EXHIBIT 3.1

ARTICLES OF AMENDMENT  OF  INTERWEST BANCORP, INC.

Pursuant to RCW 23B.10.030 and RCW 23B.10.060, the following Articles of Amendment to the Articles of Incorporation of InterWest Bancorp, Inc., are
submitted for filing.

1.  The
name of the corporation is: INTERWEST BANCORP, INC.

2.  Article I
of the Articles of Incorporation is deleted in its entirety and replaced with the following:

ARTICLE I.

The name of the corporation is Pacific Northwest Bancorp (the "corporation").

3.  The
date of adoption of the above amendment was August 17, 2000.

4.  Shareholder
action on this amendment was not required, and consequently, the amendment was adopted by the Board of Directors without shareholder approval.

5.  These
Articles of Amendment will be effective at 12:01 a.m., Pacific Standard Time, on September 1, 2000.

IN
WITNESS WHEREOF, the corporation has caused these Articles of Amendment to be executed on this 21st day of August, 2000.

| |  | INTERWEST BANCORP, INC.
| |  | -----------------------
| |  | By:                    

---

STATE of WASHINGTON

[Seal of the State of Washington]

SECRETARY of STATE

I, RALPH MUNRO, Secretary of State of the State of Washington and custodian of its seal,hereby issue this

CERTIFICATE OF AMENDMENT

to

INTERWEST BANCORP, INC.

a
Washington Profit corporation. Articles of Amendment were filed for record in this office on the date indicated below.

Restating Articles

|UBI Number: 601 591 691           |  | Date: December 16, 1998                                                                  
|--------------------------------- |  | -----------------------------------------------------------------------------------------
|[Seal of the State of Washington] |  | Given under my hand and the Seal of the State of Washington at Olympia, the State Capital
|                                  |  | /s/ Ralph MunroRalph Munro, Secretary of State                                           

---

RESTATED ARTICLES OF INCORPORATION OF  INTERWEST BANCORP, INC.

Pursuant to the provisions of Title 23B of the Revised Code of Washington, the Washington Business Corporations Act ("WBCA"), the following shall
constitute the Restated Articles of Incorporation of InterWest Bancorp, Inc., a Washington Corporation.

ARTICLE
I.Name.The name of the corporation is InterWest Bancorp, Inc. (the "corporation").

ARTICLE
II.Duration.The duration of the corporation is perpetual.

ARTICLE
III.Purpose and Powers.The nature of the business and the objects and purposes to be
transacted, promoted or carried on by the corporation are to engage in the activities of a bank holding company and in any other lawful act or business for which corporations may be organized under
the WBCA as now in existence or as such laws may hereafter be amended.

ARTICLE
IV.Capital Stock.The total number of shares of all classes of capital stock which the
corporation has authority to issue is 30,000,000 shares of common stock of no par value. The consideration for the issuance of any such shares shall be paid in full before their issuance, which
consideration shall be determined by the Board of Directors, subject only to any limitations imposed by law at the time of such issuance. Upon payment of such consideration in exchange for which the
Board of Directors has authorized the issuance of any such shares, the shares issued shall be fully paid and nonassessable. Upon authorization by the Board of Directors, the corporation may issue its
own shares in exchange for or in conversion of its outstanding shares or distribute its own shares, pro rata to its shareholders or the shareholders of one or more classes or series, to effectuate
stock dividends or splits, and any such transaction shall not require consideration.

The
holders of the common stock shall exclusively possess all voting power. Each holder of shares of common stock shall be entitled to one vote for each share held by such holder, and
there shall be no right to cumulate votes for the election of directors or for any other purpose. Each share of common
stock shall have the same relative rights as and be identical in all respects with all the other shares of common stock.

ARTICLE
V.Preemptive Rights.Holders of the capital stock of the corporation shall not be entitled to
preemptive rights with respect to any shares of the corporation which may be issued.

ARTICLE
VI.Directors.



1

---

ARTICLE
VII.Initial Directors.The names and addresses of the persons who shall serve as the Board of
Directors of the corporation until the first annual meeting of stockholders, at which time they may stand for reelection, are as follows:

Name

AddressBarney R. Beeksma

930 West Waterloo Road, Oak Harbor, WA 98277C. Stephen Lewis

28843 7th South, Federal Way, WA 98003Russel E. Olsen

9721 112th N.E., Kirkland, WA 98033Vern Sims

2133 A Bassett Road, Sedro Wolley, WA 98284Jean Gorton

213 Sea Pines Lane, Bellingham, WA 98226Henry Koetje

2123 200th Avenue S.W., #306, Oak Harbor, WA 98277Stephen M. Walden

1234 N. Lombardy Lane, Oak Harbor, WA 98277Clark H. Mock

7010 80th Avenue S.E., Mercer Island, WA 98040Michael T. Crawford

1868 Rocky Ridge Lane, Sedro Wolley, WA 98284


ARTICLE
VIII.Removal of Directors.Notwithstanding any other provisions of these articles of
incorporation or the corporation's bylaws (and notwithstanding the fact that some lesser percentage may be specified by law, these articles of incorporation or the corporation's bylaws), any director
or the entire Board of Directors may be removed only for cause and only by a majority of the directors of the corporation or by the affirmative vote of the holders of a majority of the total votes
eligible to be cast at a legal meeting called expressly for such purpose. For purpose of this Article VIII, "cause" shall mean fraudulent or dishonest acts, a gross abuse of authority in discharge of
duties to the corporation or acts that are detrimental or hostile to the interest of the corporation.

ARTICLE
IX.Registered Office and Agent.The registered office of the corporation shall be located at
1259 West Pioneer Way, Oak Harbor, Washington 98277. The initial registered agent of the corporation at such address shall be Margaret Mordhorst.

ARTICLE
X.Approval of Certain Business Combinations.The stockholder vote required to approve Business
Combinations (as hereinafter defined) shall be as set forth in this section.



2

---



3

---



ARTICLE
XI.Evaluation and Business Combinations.In connection with the exercise of its judgment in
determining what is in the best interests of the corporation and of the shareholders, when evaluating a Business Combination (as defined in Article X) or a tender or exchange offer, the board
of directors of the corporation shall, in addition to considering the adequacy of the amount to be paid in connection with any such transaction, consider all of the following factors and any other
factors which it deems relevant; (i) the social and economic effects of the transaction on the corporation and its subsidiaries, employees, depositors, loan and other customers, creditors and
other elements of the communities in which the corporation and its subsidiaries operate or are located; (ii) the business and financial condition and earnings prospects of the acquiring person
or entity, including, but not limited to, debt
service and other existing financial obligations, financial obligations to be incurred in connection with the acquisition and other likely financial obligations of the acquiring person or entity and
the possible effect of such conditions upon the corporation and its subsidiaries and the other elements of the communities in which the corporation and its subsidiaries operate or are located; and
(iii) the competence, experience, and integrity of the acquiring person or entity and its or their management.

ARTICLE
XII.Limitation of Directors' Liability.To the fullest extent permitted by Washington law, as
it now exists or may hereafter be amended, a director of this corporation shall not be personally liable to the corporation or its stockholders for monetary damages for conduct as a director, except
for liability of the director for acts or omissions that involve: (i) intentional misconduct by the director; (ii) a knowing violation of law by the director; (iii) conduct
violating Section 23B.08.310 of the Revised Code of Washington; or (iv) any transaction from which the director will personally receive a benefit in money, property or services to which
the director is not legally entitled. If the WBCA is amended in the future to authorize corporate action further eliminating or limiting the personal liability of directors, then the liability of a
director of the corporation shall be eliminated or limited to the full extent permitted by the WBCA, as so amended, without any requirement or further action by stockholders. An amendment or repeal of
this Article shall not adversely affect any right or protection of a director of the corporation existing at the time of such amendment or repeal.

4

---

ARTICLE XIII.Indemnification.The corporation shall indemnify and advance expenses to its directors,
officers, agents and employees as follows:

5

---

ARTICLE
XIV.Special Meeting of Shareholders.Special meetings of the shareholders for any purpose or
purposes may be called by the president, by the Board of Directors, or by the written request of holders of not less than a majority of all the shares of the corporation entitled to vote at the
meeting.

ARTICLE
XV.Repurchase of Shares.The corporation may from time to time, pursuant to authorization by
the board of directors of the corporation and without action by the shareholders, purchase or otherwise acquire shares of any class, bonds, debentures, note, scrip, warrants, obligations, evidences of
indebtedness, or other securities of the corporation in such manner, upon such terms, and in such amounts as the board of directors shall determine; subject, however, to such limitations or
restrictions, if any, as are contained in the express terms of any class of shares of the corporation outstanding at the time of purchase or acquisition in question or as are imposed by law.

ARTICLE
XVI.Amendment of Articles of Incorporation.The corporation reserves the right to repeal,
alter, amend or rescind any provision contained in the Articles of Incorporation in the manner now or hereafter prescribed by law, and all rights conferred on stockholders herein are granted subject
to this reservation. Notwithstanding the foregoing, the provisions set forth in Articles II, III and IV (other than a change to the number of authorized shares in connection with a split of, or
stock dividend in, the corporation's own shares, provided the corporation has only one class of shares outstanding or a change in the par value of such shares), V, VI, VIII, X, XI, XII, XIII, XIV, XV
and this Article XVI of the Articles of Incorporation may not be repealed, altered, amended or rescinded in any respect unless the same is approved by the affirmative vote of the holders of not less
than a majority of the votes entitled to be cast by each separate voting group entitled to vote thereon, cast at a meeting of stockholders called for that purpose (provided that notice of such
proposed adoption, repeal, alteration, amendment or rescission is included in the notice of such meeting).

ARTICLE
XVII.Incorporator.The name and mailing address of the incorporator is as follows:



These
Restated Articles of Incorporation of InterWest Bancorp, Inc. do not include any new amendments to the Articles of Incorporation of InterWest Bancorp, Inc. as amended. These
Restated Articles of Incorporation of InterWest Bancorp, Inc. supersede the original Articles of Incorporation of InterWest Bancorp, Inc. and all amendments thereto.

Executed
this 11th day of December, 1998.



6

---



|STATE OF WASHINGTON |  | ) |   
|------------------- |  | - | --
|                    |  | ) | ss
|County of Island    |  | ) |   

I
certify that I know or have satisfactory evidence that Stephen M. Walden is the person who appeared before me, and said person acknowledged that he signed this instrument, on oath
stated that he was authorized to execute this instrument and acknowledged it as the President of InterWest Bancorp, Inc. to be the free and voluntary act of such party for the uses and purposes
mentioned in the instrument.

DATED
this 11th day of December, 1998.

|       |  | /s/KENTON LEE DALE(Signature)                
|------ |  | ---------------------------------------------
|       |  | Kenton Lee Dale(Print)                       
|[SEAL] |  | NOTARY PUBLIC
My Appointment Expires:2/5/2000

9

---

CERTIFICATE OF CORPORATE OFFICER

Under penalty of perjury under the laws of the State of Washington, I certify the following to be true and
correct:

DATED
this 11th day of December, 1998, at Oak Harbor, Washington.

| | INTERWEST BANCORP, INC.                         
| | ------------------------------------------------
| | /s/STEPHEN M. WALDENStephen M. Walden, President

---

QuickLinks