SCHEDULE 14A INFORMATION

Proxy Statement Pursuant to Section 14(a) of the Securities Exchange Act of 1934

(Amendment No.     )

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¨ Preliminary Proxy Statement

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¨ Definitive Proxy Statement

x Definitive Additional Materials

¨ Soliciting Material Pursuant to § 240.14a-11(c) or § 240.14a-12

CLEARWATER PAPER CORPORATION

(Name of Registrant as Specified In Its Charter)

(Name of Person(s) Filing Proxy Statement, if other than the Registrant)

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*** Exercise Your Right to Vote ***

Important Notice Regarding the Availability of Proxy Materials for the

Stockholder Meeting to Be Held on May 9, 2011.

CLEARWATER PAPER CORPORATION

Meeting Information

Meeting Type: Annual Meeting

For holders as of: March 10, 2011

Date: May 9, 2011 Time: 9:00 AM PDT

Location: Grand Hyatt Seattle 721 Pine Street Seattle, WA 98101

You are receiving this communication because you hold shares in the above named company.

CLEARWATER PAPER CORPORATION 601 W. RIVERSIDE AVENUE SUITE 1100 SPOKANE, WA 99201

This is not a ballot. You cannot use this notice to vote these shares. This communication presents only an overview of the more complete proxy materials that are available to you on the Internet. You may view the proxy materials online at www.proxyvote.com or easily request a paper copy (see reverse side).

We encourage you to access and review all of the important information contained in the proxy materials before voting.

See the reverse side of this notice to obtain proxy materials and voting instructions.

Before You Vote

How to Access the Proxy Materials

Proxy Materials Available to VIEW or RECEIVE:

NOTICE AND PROXY STATEMENT

ANNUAL REPORT WITH FORM 10-K

How to View Online:

Have the information that is printed in the box marked by the arrow XXXX XXXX XXXX (located on the following page) and visit: www.proxyvote.com.

How to Request and Receive a PAPER or E-MAIL Copy:

If you want to receive a paper or e-mail copy of these documents, you must request one. There is NO charge for requesting a copy. Please choose one of the following methods to make your request:

1) BY INTERNET:

www.proxyvote.com

2) BY TELEPHONE:

1-800-579-1639

3) BY E-MAIL*:

sendmaterial@proxyvote.com

* If requesting materials by e-mail, please send a blank e-mail with the information that is printed in the box marked by the arrow XXXX XXXX XXXX (located on the following page) in the subject line.

Requests, instructions and other inquiries sent to this e-mail address will NOT be forwarded to your investment advisor. Please make the request as instructed above on or before April 25, 2011 to facilitate timely delivery.

How To Vote

Please Choose One of the Following Voting Methods

Vote In Person: Many shareholder meetings have attendance requirements including, but not limited to, the possession of an attendance ticket issued by the entity holding the meeting. Please check the meeting materials for any special requirements for meeting attendance. At the meeting, you will need to request a ballot to vote these shares.

Vote By Internet: To vote now by Internet, go to www.proxyvote.com. Have the information that is printed in the box marked by the arrow XXXX XXXX XXXX available and follow the instructions.

Vote By Mail: You can vote by mail by requesting a paper copy of the materials, which will include a proxy card.

Voting Items

The Board of Directors recommends a vote FOR the election of two Directors to serve until the 2014 Annual Meeting of Stockholders.

Proposal 1 - Election of Directors

Nominees:

1a. Fredric W. Corrigan

1b. William T. Weyerhaeuser

The Board of Directors recommends a vote FOR Proposal 2.

Proposal 2 - Ratification of the appointment of KPMG, LLP as the Company’s independent registered public accounting firm for 2011.

The Board of Directors recommends a vote FOR Proposal 3.

Proposal 3 - Say-on-Pay advisory vote.

The Board of Directors recommends a vote for a frequency of THREE years on Proposal 4.

Proposal 4 - Frequency of say-on-pay advisory vote.