St. Thomas' Episcopal Parish Historic District is a national historic district located at Croom, Prince George's County, Maryland. The district encompasses four contributing buildings and three contributing sites associated with St. Thomas' Church. The other contributing buildings are the Gothic Revival style St. Thomas' Church Rectory (1852-1853), Tenant/Sexton's House, and tobacco barn. The contributing sites are the St. Thomas' Episcopal Church Cemetery, St. Simon's Mission Chapel Site, and St. Simon's Cemetery. The African-American communicants of St. Thomas' Church formed St. Simon's Mission Chapel in the late-19th century and it operated on the property associated with the Croome Industrial and Agricultural School, which operated from about 1902 to 1952.