| Official Name: | Adelaida, California |
| Pushpin Map: | California#USA |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | California |
| Subdivision Type2: | County |
| Subdivision Name2: | San Luis Obispo |
| Timezone: | Pacific (PST) |
| Utc Offset: | -8 |
| Timezone Dst: | PDT |
| Utc Offset Dst: | -7 |
| Elevation Ft: | 1404 |
| Coordinates: | 35.6456°N -120.8736°W |
| Postal Code: | 93446 |
| Area Code: | 805 |
| Blank Name: | GNIS feature ID |
| Blank Info: | 1660231[1] |
Adelaida (pronounced as, and in the 19th century commonly spelled as Adelaide)[2] is an unincorporated community in San Luis Obispo County, California, United States. Adelaida is 10miles west of Paso Robles. The community had a post office from 1877 to 1936.[3]
In the 1880s, the population of Adelaida was approximately 500, supported by the prospering Klau and Buena Vista mercury mines. The town boasted a community center, saloon, dance hall, general store, and four schools. The population increased further in 1898 with an influx of Mennonite settlers. The Adelaida School, located near the entrance to the Osgood Ranch on Chimney Rock Road, was built in 1917. It is being restored by the Adelaida Historical Foundation.[4] This school and the Adelaida Road cemetery are all that is left of old Adelaida. Although the quicksilver mines were in operation into the 1970s, most of the local businesses had long since relocated to Paso Robles.[5]