St. Mark's School is a coeducational, Episcopal preparatory school, situated on 250 acres (100 ha) in Southborough, Massachusetts, 25 miles (40 km) from Boston. St. Mark's was founded in 1865 as an all-boys school by Joseph Burnett, who developed and marketed Burnett Vanilla Extract. Girls have attended since 1978. St. Mark's is a member of the Independent School League and one of five prep schools known collectively as St. Grottlesex.