San Luis Obispo ( /sæn ˈluːɪs ɵˈbɪspoʊ/; Spanish for St. Louis, the Bishop) is a city in California, located roughly midway between Los Angeles and San Francisco on the Central Coast. Founded in 1772 by Spanish Fr. Junípero Serra, San Luis Obispo is one of California's oldest communities. The city, referred to locally as San Luis or SLO, is the county seat of San Luis Obispo County and is adjacent to California Polytechnic State University. The population was 45,119 at the 2010 census.

Earliest human inhabitants of the local area were the Chumash peoples. One of the earliest villages lies south of San Luis Obispo, and reflects the landscape of the early Holocene when estuaries came farther inland. These Chumash people exploited marine resources of the inlets and bays along the Central Coast and inhabited a network of villages including sites at Los Osos and Morro Creek.

During the Spanish Empire expansion throughout the world, specifically in 1769, Spanish Franciscan Junípero Serra, received orders from Spain to bring the Catholic faith to the Natives of Alta California, the idea was to unify the empire under the same religion and language. Mission San Diego was the first Spanish mission founded in Alta California that same year.

San Luis, the Spanish name for Saint Louis, is a common toponym in parts of the world where that language is or was spoken. It may refer to:

San Luis may also refer to: