Legal Question in Landlord & Tenant Law in California

Well, technically no, unless the lease provides for it to become a month-to-month rental agreement after it expires (which all mine do). The agreement terminates at its expiration date, and if you hold over occupancy it becomes a common law "tenancy at will." For all intents and purposes, that's really the same thing, and there's a good argument that absent contrary evidence the parties expected to continue to be governed by the terms of the lease. But technically any terms of the lease beyond the bare rent and occupancy rights that exist under law expire. So, for example, if the lease of a single family house called for the landlord to provide a gardener, he could stop without it being breach of the no-longer-existing contract. So for the sake of clear understanding of continuing rights and responsibilities, it's far better either to have an automatic roll-over to month-to-month in the lease, or sign a new lease or month-to-month agreement at the expiration of the lease.