San Anselmo is an incorporated town in Marin County, California, in the western United States. San Anselmo is located 1.5 miles west of San Rafael, at an elevation of 46 feet. It is located about 20 miles north of San Francisco. Neighboring towns include San Rafael and Greenbrae to the east, Fairfax to the west, and Ross to the south. Mount Tamalpais dominates the view to the south.

All but a sliver of San Anselmo lies within the 28-square-mile Ross Valley Watershed that flows into San Francisco Bay. There are three main roads running through San Anselmo. Their junction is known locally as the Hub, which lies near the central business district. The town’s natural skyline is dominated by the hills of Ross Valley. To the north are Red Hill and Grove Hill. To the south-west is Bald Hill. To the east is Moore Hill. In the distance to the south is Mount Tamalpais.

San Anselmo is home to a variety of schools.