It is an independent school located in the Archdiocese of Philadelphia and was previously known as the "Mater Misericordiae Academy" prior to 1968.

Recent events include the merger of the lower school with Waldron Academy for Boys next door in 1987, thereby giving the entire 72,000-square-foot (6,700 m2) Merion Mercy building, built in 1954, to the education of high school girls.

A 27,000-square-foot (2,500 m2) addition to the MMA building in 2003 added a new chapel, administrative offices, classrooms and meeting rooms, new athletic facilities, and a study center for students.

The current head of school is Marianne Grace, a former chair of the Board of Trustees, and previous Director of Operation.

The very next year the basketball team won the state PIAA Class AA championship.