St. Mary's is a Roman Catholic primary school in Crescent Lane, Clapham, South London, England. Until 1992 the school was split over two sites as junior boys were based at St. Alphonsus Road, Clapham, but the St. Alphonsus Road site has since closed and all pupils are now based at Crescent Lane. The school maintains strong links with St. Mary's Roman Catholic Church, Clapham, after which it was named.