Mother Seton Regional High School (often referred to as Mother Seton) is an all-girl Catholic high school located in Clark, in Union County, New Jersey, United States. It is located in 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 1971. The school is staffed by the Sisters of Charity of Convent Station, New Jersey, and lay faculty members. The school occupies a two-level building located on a campus of 27 acres (110,000 m2).