Stevenson Ranch is an unincorporated area in Los Angeles County, California. The community is located in the Santa Clarita Valley. Stevenson Ranch is set in the foothills of the Santa Susana Mountains and lies west of Interstate 5 and the city of Santa Clarita. Stevenson Ranch encompasses about . About are set aside as parks, recreation areas, and open space. A master-planned community, it was approved by the county in 1987. The population was 17,557 at the time of the 2010 census. For statistical purposes, the Census Bureau has designated it a census-designated place.