Mount Saint Mary Academy is a four-year private high school for girls, located in Watchung, in Somerset County, New Jersey, United States. Located in the Roman Catholic Diocese of Metuchen, the school operates financially independent of the Diocese. The Academy was founded in 1908 by the Sisters of Mercy of New Jersey and opened with 77 students. A fire destroyed the main building in 1911, but the school reopened in the following year and has grown steadily. In the 1980s and 1990s it was a boarding school that housed local, out of state and international students.