Oak Park is an unincorporated community in southeastern Ventura County, California, United States. When developed in the Simi Hills in the late 1960s, a single road provided the only access to the community from Agoura Hills, California, in neighboring Los Angeles County. As of the 2010 census, Oak Park had a population of 14,266, down from 14,625 at the 2000 census. For statistical purposes, the United States Census Bureau has defined Oak Park as a census-designated place.