Rancho Santa Margarita was a 17,735-acre (71.77 km2) Mexican land grant in the Santa Lucia Mountains, in present day San Luis Obispo County, central California.
The rancho was granted by Governor pro tem Manuel Jimeno Casarin in 1841 to Joaquín Estrada.[1] The grant encompassed present day Santa Margarita.[2][3] It remains an active ranch.