Rancho Guadalasca was a 30,594-acre (123.81 km2) Mexican land grant in present-day Ventura County, California given in 1836 by Governor Mariano Chico to Ysabel Yorba. The grant was in the southern part of the county, bordering on Los Angeles County. The grant extended along the Pacific coast near Point Mugu for about eight miles, and extending into the interior along Guadalasca Creek in the Santa Monica Mountains for about ten miles.