Exhibit 11

WESTAMERICA BANCORPORATION

Computation of Earnings Per Share on Common and
Common Equivalent Shares and on Common Shares
Assuming Full Dilution

(In thousands, except per share data)	2005		2004		2003
Weighted average number of common shares outstanding — basic		32,291		31,821		32,849
Add exercise of options reduced by the number of shares that could have been purchased with the proceeds of such exercise		606		640		520
Weighted average number of common shares outstanding — diluted		32,897		32,461		33,369
Net income	$	107,441	$	95,218	$	95,063
Basic earnings per share	$	3.33	$	2.99	$	2.89
Diluted earnings per share		3.27		2.93		2.85