Immaculate Conception High School is a Roman Catholic coeducational college preparatory high school located in Montclair, in Essex County, New Jersey, United States. The school operates under the supervision of the Roman Catholic Archdiocese of Newark. The school has been accredited by the Middle States Association of Colleges and Schools Commission on Secondary Schools since 1957. As of the 2013-14 school year, the school had an enrollment of 179 students and 24.4 classroom teachers (on an FTE basis), for a student–teacher ratio of 7.31.