Saint John's Catholic Prep (also known as St. John's Literary Institution) is a private, Roman Catholic, coeducational, college preparatory high school in Buckeystown, Maryland, currently located just southwest of Frederick City. At the time of its founding in 1829, it was located on Second Street in eastern downtown Frederick. Beginning in 1958 and for 45 years thereafter, the school was housed in the historic "Prospect Hall" mansion, (1787–1803), also just southwest of Frederick. St. John's was the first independent Roman Catholic school in the state of Maryland.