The government of California is the governmental structure of the U.S. state of California as established by the California Constitution. California uses the separation of powers system to structure its government. It is composed of three branches: the executive, consisting of the governor of California and the other constitutionally elected and appointed officers and offices; the legislative, consisting of the California State Legislature, which includes the Assembly and the Senate; and the judicial, consisting of the Supreme Court of California and lower courts. There is also local government, consisting of counties, cities, special districts, and school districts, as well as government entities and offices that operate independently on a constitutional, statutory, or common law basis. The state also allows direct participation of the electorate by initiative, referendum, recall and ratification.

The Constitution of California is the primary organizing law for the U.S. state of California, describing the duties, powers, structures and functions of the government of California. California's constitution was drafted in both English and Spanish by American pioneers, European settlers, and Californios and adopted at the 1849 Constitutional Convention of Monterey, following the American Conquest of California and the Mexican–American War and in advance of California's Admission to the Union in 1850. The constitution was amended and ratified on 7 May 1879, following the Sacramento Convention of 1878–79.