Rancho Santa Margarita is an affluent city in Orange County, California. One of Orange County’s youngest cities, Rancho Santa Margarita is a master planned community set upon rolling hills. Most neighborhoods in Rancho Santa Margarita are within various homeowners associations. The population was 47,853 at the 2010 census, up from 47,214 at the 2000 census.
Although it is named for Rancho Santa Margarita y Las Flores, which was in San Diego County, the city limits fall within the borders of Rancho Mission Viejo.