San Anselmo
- County:
- Marin County
- County Seat:
- No
- Area (mi²):
- 2.675
- State:
- California
San Anselmo is a town located in Marin County, California. San Anselmo has a 2026 population of 12,645. San Anselmo is currently growing at a rate of 0.6% annually but its population has decreased by -1.33% since the most recent census, which recorded a population of 12,815 in 2020.