Oak Park is an unincorporated community in Ventura County, California, United States. When developed in the Simi Hills in the late 1960s, a single road provided the only entrance to the community from Agoura Hills, California, in next to 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 (CDP). The census definition of the Place may not precisely tie in to local deal of the area with the same name.

Oak Park is the biggest unincorporated community in Ventura County. Residents of the community have through votes declined to set up an independent city, and then declined to be annexed into adjacent to Thousand Oaks.

Oak Park has had human pastime from about 5500 B.C. to the present day. It lies within a zone including the in advance Millingstone Horizon and inland Chumash Indians. Indians camped throughout the area as they collected acorns, yucca, and new food. The sites in the Place include major villages, smaller camps and several stone shelters. Chumash people lived here for thousands of years prior to European contact. They lived off of trading, gathering and hunting. The Chumash originally contracted in Oak Park due to an abundance of natural resources, including fresh water, acorns and rabbit-hunting. It is one of the oldest occupied places in California.

The location of Oak Park was originally allowance of Rancho Simi, a Spanish land concession in Alta California total in 1795 to Francisco Javier Pico, a soldier of the Santa Barbara company, and his two brothers, Patricio Pico and Miguel Pico by the Spanish government. Lindero Canyon Road follows the western border-line (lindero in Spanish) of the land grant.