If you're coming here from somewhere else, and you have a vehicle that was registered in another state, you'll need to get it registered here within 20 days of your first day of residency or at a new job.

To register an out-of-state vehicle in California, you'll need:

1. a completed and signed Application for Title or Registration.
2. verification of the vehicle (this is generally completed by the DMV).
3. out-of-state title or registration card.
4. smog certification (only for cars 1976 and newer).
5. weight certificate (only for commercial vehicles and vehicles that have put on 20 or more pounds since high school).
6. whatever DMV fees are required.
7. a completed Odometer Mileage Disclosure statement (if applicable).

Get all of that taken care of and you're officially a California driver. Good luck out there—you're going to need it.