Item 8.01. Other Events.

On August 3, 2009, Columbia Banking System, Inc. (the "Company") announced that it expects to offer and sell approximately $80 million of common stock in an underwritten public offering. The offer and sale would be made pursuant to the Company's shelf registration statement on Form S-3, filed with the Securities and Exchange Commission on October 17, 2008. Keefe, Bruyette & Woods, Inc. is serving as lead book-running manager of the offering, and D.A. Davidson & Co. is a co-manager. Columbia Banking System intends to grant the underwriters a 30-day option to purchase up to an additional 15% of the shares sold to cover over-allotments, if any.

A copy of the press release is attached as Exhibit 99.1 to this Report, and is incorporated herein by reference in its entirety.

Item 9.01. Financial Statements and Exhibits.

(d) Exhibits.

99.1 Press Release dated August 3, 2009

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