Home Inspector Licensing in California

Voluntary, but the industry standard
California doesn't license home inspectors, so most working inspectors join a national professional association to demonstrate training and adherence to a published standard. The two largest are the American Society of Home Inspectors (ASHI) and the International Association of Certified Home Inspectors (InterNACHI). Both offer training, certification, ongoing CE, and member support.

InterNACHI

ASHI

Required by Business and Professions Code §7195–7199
Although California doesn't license home inspectors, all inspectors must comply with the Trade Practice Act. The law prohibits inspectors from repairing properties they have inspected within the previous 12 months, invalidates contractual provisions that limit inspector liability to the cost of the report, and allows courts to consider published Standards of Practice when evaluating an inspection's standard of care. Compliance is not optional — it applies to every home inspector working in the state.

Required
BPC §7195–7199

Strongly recommended even though not required
California doesn't mandate insurance, but working inspectors typically carry general liability of $100K–$300K and errors & omissions (E&O) coverage of $250K–$500K. Most lenders, real estate brokerages, and home warranty companies require proof of coverage before referring you business — so insurance is functionally required even where it's legally optional.

Note: under the Trade Practice Act, contracts that limit your liability to the cost of the inspection are invalid.

Recommended 

California Real Estate Inspection Association (CREIA)
creia.org