Westamerica Bancorp. is a bank holding company. The company provides a full range of banking services to individual and corporate customers in Northern and Central California through its subsidiary banks, Westamerica Bank and Bank of Lake County. It also owns Westamerica CommercialCredit, Inc., a company engaged in financing accounts receivable and inventory lines of credit and term business loans and Community Banker Services Corporation, a company engaged in providing the companyand its subsidiaries data processing services and other support functions.