St Mary's High School is a secondary school situated in Limavady, County Londonderry, Northern Ireland. It is one of three secondary schools in Limavady, the others being, Limavady High School and Limavady Grammar School. St. Mary's however is predominantly Roman Catholic. St. Mary's is the only Catholic secondary school in Limavady, and has close ties with St. Mary's chapel which is opposite the school. The principal is Mrs. Mary McCloskey.