Two Rock is an unincorporated community in Sonoma County, California, United States. It is located on Stemple Creek in a rural area west of Petaluma. A hill named Dos Piedras (Spanish for "two rocks", 157 feet (48 m) above sea level) overlooks the community from the north. The community is named for the two rocks, between which the Mexican trail from San Rafael to Bodega passed. Two Rock had a post office located at the intersection of Bloomfield and Tomales Road, as well as a school 1.3 miles west of the former post office, on Tomales Road. A new school has since been built further east, but the original school building still stands.[2][3]
The main road is Valley Ford Road, which passes northwest–southeast through Two Rock. The Coast Guard's Training Center Petaluma is located just south of Two Rock. Two Rock used to provide basic services to local ranches, but little remains today.[4]