S-3MEF

As filed with the Securities and Exchange Commission on August 5, 2009

Registration No. 333-______

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D. C. 20549

FORM S-3

REGISTRATION STATEMENT

UNDER

THE SECURITIES ACT OF 1933

COLUMBIA BANKING SYSTEM, INC.

(Exact name of registrant as specified in its charter)

Washington	91-1422237
(State or jurisdiction of incorporation or organization)	(I.R.S. Employer Identification No.)

1301 “A” Street, Tacoma, Washington 98402-4200 (253) 305-1900

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

Melanie J. Dressel

President and Chief Executive Officer

1301 “A” Street

Tacoma, Washington 98402-4200

(253) 305-1900

(Name, address, including zip code, and telephone number, including area code, of agent for service)

Copies of Communications to:

Stephen M. Klein

Casey M. Nault

Graham & Dunn PC

Pier 70

2801 Alaskan Way, Suite 300

Seattle, Washington 98121

Approximate date of commencement of proposed sale to the public: From time to time after the effective date of this Registration Statement.

If the only securities being registered on this form are being offered pursuant to dividend or interest reinvestment plans, check the following box:    ¨

If any of the securities being registered on this form are to be offered on a delayed or continuous basis pursuant to Rule 415 under the Securities Act of 1933, other than securities offered only in connection with dividend or reinvestment plans, check the following box.    x

If this form is filed to register additional securities for an offering pursuant to Rule 462(b) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    x 333-154418

If this form is a post-effective amendment filed pursuant to Rule 462(c) under the Securities Act, check the following box and list the Securities Act registration statement number of the earlier effective registration statement for the same offering.    ¨

If this form is a registration statement pursuant to General Instruction I.D. or a post-effective amendment thereto that shall become effective upon filing with the Commission pursuant to Rule 462(e) under the Securities Act, check the following box.    ¨

If this form is a post-effective amendment to a registration statement filed pursuant to General Instruction I.D. filed to register additional securities or additional classes of securities pursuant to Rule 413(b) of the Securities Act, check the following box.    ¨

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (Check one):

Large accelerated filer    ¨     Accelerated filer    x Non-accelerated filer    ¨ Smaller reporting company    ¨

                            (Do not check if a smaller reporting company)

CALCULATION OF REGISTRATION FEE

Title of Securities to be Registered	Amount to be Registered(1)(2)	Proposed maximum offering price per Share(1)(2)	Proposed Maximum Aggregate Offering Price(1)(2)(3)	Amount of Registration Fee(3)
Common Stock, No Par Value per Share (4)
Preferred Stock, No Par Value per share (5)
Total	$20,000,000	100%	$20,000,000	$1,116.00

(1) The $20,000,000 aggregate amount being registered is in addition to the $100,000,000 aggregate amount originally registered, all of which remains available for issuance, under the Registrant’s Registration Statement on Form S-3 (File No. 333-154418) filed with the Securities and Exchange Commission on October 17, 2008. In no event will the aggregate initial offering price of all securities issued under this Registration Statement exceed $20,000,000.

(2) Certain information as to each class of securities to be registered is not specified, in accordance with General Instruction II.D to Form S-3 under the Securities Act of 1933 (“Securities Act”).

(3) The proposed maximum aggregate offering price has been estimated solely to calculate the registration fee under Rule 457(o) of the Securities Act.

(4) Subject to note (1) above, the Registrant is registering an indeterminate number of shares of common stock as may be sold from time to time by the Registrant. The Registrant is also registering an indeterminate number of shares of common stock as may be issuable upon conversion of any preferred stock.

(5) Subject to note (1) above, the Registrant is registering an indeterminate number of shares of preferred stock as may be sold from time to time by the Registrant.

This Registration Statement shall become effective upon filing with the Commission in accordance with Rule 462(b) under the Securities Act.

EXPLANATORY NOTE

This Registration Statement is being filed with the Securities and Exchange Commission (the “Commission”) pursuant to Rule 462(b) under the Securities Act of 1933, as amended, and General Instruction IV.A to Form S-3.

This Registration Statement relates to the shelf registration statement on Form S-3 (File No. 333-154418) (the “Prior Registration Statement”) filed by the Registrant on October 17, 2008 and declared effective on November 3, 2008 by the Commission, and is being filed for the purpose of increasing the dollar amount of securities registered under the Prior Registration Statement by $20,000,000. The contents of the Prior Registration Statement, including the exhibits thereto and each of the documents incorporated by reference therein, are incorporated herein by reference in their entirety.

The required opinions and consents are listed on an Exhibit Index attached hereto and filed herewith.

II-1

SIGNATURES

Pursuant to the requirements of the Securities Act of 1933, the Registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-3 and has duly caused this Registration Statement to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Tacoma, State of Washington on August 5, 2009.

COLUMBIA BANKING SYSTEM, INC.
By:	/s/ Melanie J. Dressel
	Melanie J. Dressel President and Chief Executive Officer

Pursuant to the requirements of the Securities Act of 1933, this Registration Statement has been signed by the following persons in the capacities indicated, on August 5, 2009.

/s/ Melanie J. Dressel

Melanie J. Dressel, President and

Chief Executive Officer and Director

(Principal Executive Officer)

/s/ Gary R. Schminkey

Gary R. Schminkey, Executive Vice President and Chief Financial Officer

(Principal Financial and Accounting Officer)

*

William T. Weyerhauser, Chairman of the Board and Director

*

Thomas M. Hulbert, Director

*

Daniel C. Regis, Director

*

Donald Rodman, Director

*By:	/s/ Melanie J. Dressel
	Melanie J. Dressel Attorney-in-fact

II-2

EXHIBIT INDEX

Exhibit No.	Description of Exhibits
5.1	Opinion of Graham & Dunn PC regarding legality of securities
23.1	Consent of Graham & Dunn PC (contained in its opinion filed as Exhibit 5.1)
23.2	Consent of Deloitte & Touche LLP, independent registered public accounting firm
24.1	Power of Attorney (1).

⁽¹⁾Previously filed on the signature page to the Registrant’s registration statement on Form S-3 (File No. 333-154418) filed by the Registrant with the Commission on October 17, 2008 and incorporated herein by reference.

II-3

EX-5.1

August 5, 2009

The Board of Directors

Columbia Banking System, Inc.

1301 “A” Street

Tacoma, Washington 98402

Re: Registration Statement on Form S-3 to Register an Additional $20,000,000 in

Securities Relating to Prior Registration Statement on Form S-3 (SEC File No.

333-154418)

Ladies and Gentlemen:

We have acted as special counsel for Columbia Banking System, Inc., a Washington corporation (“Columbia”), in connection with the registration under the Securities Act of 1933, as amended (the “Act”), of up to an aggregate of $20,000,000 of common and preferred shares of Columbia, no par value per share (the “Shares”), covered by the above-referenced Registration Statement and any amendments thereto (the “Registration Statement”) to be filed by Columbia with the Securities and Exchange Commission (the “Commission”) under the Act.

In connection with the Shares that will be registered and issued under the Registration Statement, we have examined the following: (i) the Registration Statement to be filed by Columbia with the Commission; (ii) resolutions adopted by the Board of Directors of Columbia (“Board of Directors”) relating to the authorization and approval of the registration of the Shares under the Registration Statement; and (iii) such other documents as we have deemed necessary to form the opinion expressed below. As to various questions of fact material to such opinion, where relevant facts were not independently established, we have relied upon statements of officers of Columbia or representations of Columbia contained or incorporated by reference in the Registration Statement. We have assumed, without independent investigation or review, the accuracy and completeness of the facts and representations and warranties contained in the documents listed above or otherwise made known to us.

Our opinion assumes that the issuance of Shares covered by the Registration Statement by Columbia from time to time will be approved by the Board of Directors, in accordance with Washington law and the Articles of Incorporation and Bylaws of Columbia (such approval being referred to herein as the “Corporate Proceedings”).

Columbia Banking System, Inc.

August 5, 2009

Page 2

Based upon and relying solely upon the foregoing, we advise you that in our opinion, upon completion of all Corporate Proceedings relating to the Shares, or any portion thereof, the Shares will be (assuming that, upon issuance, the total number of Shares issued and outstanding will not exceed the total number of Shares that Columbia is then authorized to issue under its Articles of Incorporation) duly authorized and, when and if delivered against payment therefor in accordance with the Corporate Proceedings, will be validly issued under the laws of the State of Washington, and will be fully paid and nonassessable.

We assume no obligation to supplement this opinion if any applicable law changes after the date hereof or if we become aware of any fact that might change the opinion expressed herein after the date hereof.

This opinion letter is limited to the application of the laws of the State of Washington and the federal laws of the United States of America, and we express no opinion as to the laws of any other jurisdictions.

We hereby consent to the filing of this opinion as an exhibit to the Registration Statement and to the legal reference to this firm under the caption “Legal Matters” as having passed upon the validity of the Shares. In giving such consent, we do not thereby admit that we are experts within the meaning of the Act.

Very truly yours,

/s/ Graham & Dunn PC

EX-23.2

CONSENT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

We consent to the incorporation by reference in this Registration Statement on Form S-3 of our reports dated February 27, 2009 relating to the financial statements of Columbia Banking System, Inc. and the effectiveness of Columbia Banking System Inc.’s internal control over financial reporting, appearing in the Annual Report on Form 10-K for the year ended December 31, 2008 and incorporated by reference in the Prospectus included in Registration Statement No. 333-154418.

DELOITTE & TOUCHE LLP

/s/ Deloitte & Touche LLP

Seattle, Washington

August 5, 2009