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                              UNITED STATES
                    SECURITIES AND EXCHANGE COMMISSION
                          Washington, DC 20549


                                 FORM 8-K


                         CURRENT REPORT PURSUANT
                       TO SECTION 13 OR 15(D) OF THE
                      SECURITIES EXCHANGE ACT OF 1934

              Date of Report (Date of earliest event reported):
                             July 11, 2008
                             -------------

                       WESTAMERICA BANCORPORATION
                       --------------------------
          (Exact Name of Registrant as Specified in Its Charter)

                                CALIFORNIA
                                ----------
              (State or Other Jurisdiction of Incorporation)


                001-9383                       94-2156203
                --------                       ----------
        (Commission File Number)    (IRS Employer Identification No.)


         1108 Fifth Avenue, San Rafael, California          94901
         ----------------------------------------------------------
          (Address of Principal Executive Offices)        (Zip Code)


                             (707) 863-6000
                             --------------
            (Registrant's Telephone Number, Including Area Code)


   Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any
of the following provisions:

      []  Written communications pursuant to Rule 425 under the Securities
          Act (17 CFR 230.425)

      []  Soliciting material pursuant to Rule 14a-12 under the Exchange
          Act (17 CFR 240.14a-12)

      []  Pre-commencement communications pursuant to Rule 14d-2(b) under
          the Exchange Act (17 CFR 240.14d-2(b))

      []  Pre-commencement communications pursuant to Rule 13e-4(c) under
          the Exchange Act (17 CFR 240.13e-4c))


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Form 8-K

Item 2.02, Results of Operations and Financial Condition

Westamerica Bancorporation (NASDAQ: WABC) will release results of operations for
the second quarter 2008 and financial condition as of June 30, 2008 on July 15,
2008 at approximately 8:00 a.m. Pacific Time. Westamerica will report an "other
than temporary impairment" (OTTI) charge against earnings totaling $18.2
million, or $10.5 million after tax, related to various FHLMC and FNMA preferred
stock securities. This charge has not reduced Westamerica Bancorporation's
shareholders' equity since the securities have routinely been carried at market
value on the Company's balance sheet. Following this impairment charge, the
securities will have a carrying value of $44.5 million.

Westamerica expects to report the following results of operations and financial
condition following the second quarter 2008. Second quarter 2008 EPS of $0.42
including the OTTI charge, which reduced EPS $0.35. A second quarter 2008 net
interest margin of 5.16 percent, up 0.37 percent from the first quarter 2008 due
to a lower cost of funds. June 30, 2008 classified loans totaling $33.5 million,
essentially unchanged from $33.3 million at March 31, 2008. June 30, 2008 non-
performing loans of $12.0 million, or 0.49 percent of total loans, and a loan
loss reserve to total loans ratio of 2.10 percent. During the second quarter
2008, shareholders' equity growth of $10 million due to the retention of
earnings in excess of shareholder dividends, which were increased by the Board
of Directors in April 2008. Total regulatory capital as of June 30, 2008 of 11.4
percent for Westamerica Bancorporation and 10.9 percent for Westamerica Bank,
both ratios continuing to surpass the "well capitalized" threshold of 10.0
percent.

FORWARD-LOOKING INFORMATION:

The following appears in accordance with the Private Securities Litigation
Reform Act of 1995:

This press release may contain forward-looking statements about the Company,
including descriptions of plans or objectives of its management for future
operations, products or services, and forecasts of its revenues, earnings or
other measures of economic performance. Forward-looking statements can be
identified by the fact that they do not relate strictly to historical or current
facts. They often include the words "believe," "expect," "anticipate," "intend,"
"plan," "estimate," or words of similar meaning, or future or conditional verbs
such as "will," "would," "should," "could," or "may."

Forward-looking statements, by their nature, are subject to risks and
uncertainties. A number of factors - many of which are beyond the Company's
control - could cause actual conditions, events or results to differ
significantly from those described in the forward-looking statements. The
Company's most recent annual and quarterly reports filed with the Securities and
Exchange Commission, including the Company's Form 10-Q for the quarter ended
March 31, 2008 and Form 10-K for the year ended December 31, 2007, describe some
of these factors, including certain credit, market, operational, liquidity and
interest rate risks associated with the Company's business and operations. Other
factors described in these reports include changes in business and economic
conditions, competition, fiscal and monetary policies, disintermediation,
legislation including the Sarbanes-Oxley Act of 2002 and the Gramm-Leach-Bliley
Act of 1999, and mergers and acquisitions.

Forward-looking statements speak only as of the date they are made. The Company
does not undertake to update forward-looking statements to reflect circumstances
or events that occur after the date forward looking statements are made.


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                              Signatures

Pursuant to the Securities Exchange Act of 1934, the registrant has duly caused
this report to be signed on its behalf by the undersigned hereunto duly
authorized.

Westamerica Bancorporation

/s/    JOHN "ROBERT" THORSON
-------------------------------------------------
John "Robert" Thorson
Senior Vice President and Chief Financial Officer
July 11, 2008