SecProbe.io

November 18, 2011
Via E-Mail

Melanie J. Dressel Chief Executive Officer Columbia Banking System, Inc. 1301 A Street  Tacoma, WA 98402
Re: Columbia Banking System, Inc.
 Form 10-K for the Fiscal Year Ended December 31, 2010
Filed March 1, 2011 Form 10-Q for the Fiscal Qu arter Ended September 30, 2011
Filed November 8, 2011 Response dated October 31, 2011 File No. 000-20288

Dear Ms. Dressel:
We have reviewed your supplemental res ponse to our letter dated August 31, 2011 and
have the following comments.  In our comments, we may ask you to provide us with information so we may better understand your disclosure.
 Please respond to this letter within ten business days by amending your filing, by
providing the requested information, or by advi sing us when you will provide the requested
response.  Where we have specif ically requested a draft of your proposed disclosures in future
filings, please ensure that it clearly identifies new, revised or deleted disclo sures, as appropriate.
If you do not believe our comments apply to your facts and circumstances or do not believe an
amendment is appropriat e, please tell us why in your response.

After reviewing any amendment to your filing and the information you provide in
response to these comments, including the draf t of your proposed disclosures, we may have
additional comments.

Melanie J. Dressel
Columbia Banking System, Inc.
 November 18, 2011  Page 2

 Form 10-Q for the Period Ended September 30, 2011

Item 1. Financial Statements (unaudited)

Notes to Unaudited Consolidated Condensed Financial Statements

Note  8. Covered Assets and FD IC Loss Sharing Asset, page 21

1. Please provide us with and revise future filings to include a rollforward of the allowance for
loan losses as it relates to covere d loans for the periods presented.
 2. We note the information provided in response to  prior comments fifteen through seventeen in
the letter dated August 31, 2011.  Based on the le vel of information supplementally provided
and given the ongoing and significa nt level of FDIC Assisted Transactions in which the
Company has entered into, please provide us w ith and revise future filings to include a
rollfoward of your loans accounted for under AS C 310-30 which reconciles your contractual
receivable to your carrying amount for each of the periods presented.  Your revised
disclosures should also include disaggregated information pertaining to your nonaccretable
yield.

3. Please provide us with and revise future filings to include more detailed information as it
relates to the FDIC Loss Sharing Asset rollfor ward, individually iden tifying and quantifying
the amount the change in expected cash flows has on the asset. You should also specifically
discuss in detail the “other” adjustments which impact the carrying value of this asset.
 You may contact David Irving at (202) 551-3321 or Marc Thomas at (202) 551-3452 if
you have any questions.
Sincerely,
   /s/ Marc Thomas
Marc Thomas
        Review Accountant