Rancho Lompoc was a 42,085-acre (170.31 km2) Mexican land grant in present-day Santa Barbara County, California given in 1837 by Governor Juan B. Alvarado to Joaquín Carrillo and José Antonio Carrillo.
The Carrillo brothers were also granted Rancho Mission Vieja de la Purisma.
With the cession of California to the United States following the Mexican-American War, the 1848 Treaty of Guadalupe Hidalgo provided that the land grants would be honored.
As required by the Land Act of 1851, a claim for Rancho Lompoc was filed with the Public Land Commission in 1853,[5][6] and the grant was patented to Joaquín Carrillo and José Antonio Carrillo in 1873.
The droughts of the early 1860s forced the More brothers to dissolve their partnership and divide up their lands.