St. Mary of the Assumption High School is a small Catholic high school on Broad Street in Elizabeth, in Union County, New Jersey, United States. The old high school building consists of a three-story brick building with a basement serving as additional classroom space for a total of four floors of education space. The school is affiliated with its parent parish, St. Mary's Church, and operates under the auspices of the Roman Catholic Archdiocese of Newark. The school has been accredited by the Middle States Association of Colleges and Schools Commission on Elementary and Secondary Schools since 1992.