Mount St. Mary High School is a private, Roman Catholic co-educational high school in Oklahoma City, Oklahoma, United States. It was established in 1903 by the Sisters of Mercy and located in the Roman Catholic Archdiocese of Oklahoma City.
The original school was founded by 5 Sisters of Mercy in Shawnee, what was known at the time as Indian Territory. They relocated the school of Oklahoma City in 1903 as the original school had been destroyed in a fire two years earlier. It started as a school for girls, boarding at first, followed by day students.
In 1950, as a result of the reorganization of Catholic schools throughout the Oklahoma City archdiocese, itÃÂ was agreed that boys would be admitted as well as girls.