One of Orange County's youngest cities, Rancho Santa Margarita is a master-planned community.

[6][7] In 1810, the Trabuco Adobe was constructed near the village as an outpost of Mission San Juan Capistrano.

Hughes Aircraft Company's Microelectronic Systems Division moved to Rancho Santa Margarita in May 1988 from Irvine.

In August 1992, the Hughes plant closed its facilities and moved the division to Carlsbad, California due to budget constraints in the aerospace industry.

According to the United States Census Bureau, the city has a total area of 13.0 square miles (34 km2).

Rancho Santa Margarita is bordered by the city of Mission Viejo on the west, the census-designated places Coto de Caza and Las Flores on the south, the unincorporated Trabuco Canyon on the north, and the Cleveland National Forest on the east.

Vehicular access is provided by California State Route 241 (a toll road), in addition to several surface streets.

The educational attainment level in Rancho Santa Margarita significantly exceeds the averages throughout the rest of California.

During 2009–2013, Rancho Santa Margarita had a median household income of $104,113, with 3.9% of the population living below the federal poverty line.

[38] According to the California Secretary of State, as of February 10, 2019, Rancho Santa Margarita has 28,462 registered voters.

[39] Rancho Santa Margarita has voted Republican in every presidential election since the city's incorporation.

A map of Orange County seen in season four of Arrested Development places the fictional Bluth Company-developed community of Sudden Valley northeast of Mission Viejo and Las Flores, in the approximate location of Rancho Santa Margarita.