The California Contractor's State License Board has a document, "What You Should Know before you hire a contractor", on their web site at http://www.cslb.ca.gov/forms/wysk.pdf. This is a "Must read" for a homeowner seeking to hire a contractor.

The California Contractor’s State License Board web page at http://www.cslb.ca.gov/ will allow you to check contractor's licenses, allow you to file a complaint, help you find appropriate construction laws and regulations and furnish owner/builder information.