Community property is a marital property regime that originated in civil law jurisdictions and is now also found in some common law jurisdictions. The states of the United States that recognize community property are primarily in the West; it was inherited from Mexico's ganancial community system, which itself was inherited from Spanish law (a Roman-derived civil law system) and ultimately from the Visigoths. Even Louisiana, in a rare departure from the Napoleonic code, was forced to adopt the ganancial community system while under Spanish rule (renamed "community of acquests and gains"), thus ousting the traditional French community of movables and acquests.

In a community property jurisdiction, most property acquired during the marriage (except for gifts or inheritances)—the community, or communio bonorum—is owned jointly by both spouses and is divided upon divorce, annulment or death. Joint ownership is automatically presumed by law in the absence of specific evidence that would point to a contrary conclusion for a particular piece of property. The community property system is usually justified by the idea that such joint ownership recognizes the theoretically equal contributions of both spouses to the creation and operation of the family unit.