St. Mary's is a civil parish in County Westmeath, Ireland. It is located about 19.84 kilometres (12 mi) north–north–east of Mullingar. St. Mary's is one of 8 civil parishes in the barony of Fore in the Province of Leinster. The civil parish covers 4,290.6 acres (17.363 km2). St. Mary's civil parish comprises 7 townlands: , , , , , and . The neighbouring civil parishes are: (County Meath) to the north, Delvin to the east, Clonarney to the east and south, Kilcumny to the south and St. Feighin's to the west.