San Luis Obispo County, officially the County of San Luis Obispo, is a county on the Central Coast of California. As of the 2020 census, the population was 282,424.The county seat is San Luis Obispo.

Junípero Serra founded the Mission San Luis Obispo de Tolosa in 1772, and San Luis Obispo grew around it. The small size of the county’s communities, scattered along the beaches, coastal hills, and mountains of the Santa Lucia range, provides a wide variety of coastal and inland hill ecologies to support fishing, agriculture, and tourist activities.

California Polytechnic State University has almost 20,000 students. Tourism, especially for the wineries, is popular. Grapes and other agricultural products are an important part of the economy. San Luis Obispo County is the third largest producer of wine in California, surpassed only by Sonoma and Napa counties. Strawberries are the largest agricultural crop in the county.

The town of San Simeon is located at the foot of the ridge where newspaper publisher William Randolph Hearst built Hearst Castle. Other coastal towns (listed from north to south) include Cambria, Cayucos, Morro Bay, and Los Osos -Baywood Park. These cities and villages are located northwest of the city of San Luis Obispo. To the south are Avila Beach and the Five Cities region. The Five Cities originally were: Arroyo Grande, Grover Beach (then known as Grover City), Oceano, Fair Oaks and Halcyon. Today, the Five Cities region consists of Pismo Beach, Grover Beach, Arroyo Grande, Oceano, and Halcyon (basically the area from Pismo Beach to Oceano). Just south of the Five Cities, San Luis Obispo County borders northern Santa Barbara County. Inland, the cities of Paso Robles, Templeton, and Atascadero lie along the Salinas River, near the Paso Robles wine region. San Luis Obispo lies south of Atascadero and north of the Five Cities region.