Cathedral Preparatory School and Seminary is a Roman Catholic high school and seminary in Elmhurst, Queens in New York City. It is operated by the Diocese of Brooklyn. It is the last full-time high school seminary day school in operation in the United States.

The Diocese of Brooklyn is a Latin Church ecclesiastical territory or diocese of the Catholic Church in the U.S. state of New York. It is headquartered in Brooklyn and its territory encompasses the New York City boroughs of Brooklyn and Queens. The Diocese of Brooklyn is a suffragan diocese in the ecclesiastical province of the metropolitan Archdiocese of New York. The diocesan cathedral is the Cathedral Basilica of St. James in Downtown Brooklyn and its co-cathedral is the Co-Cathedral of St. Joseph in Prospect Heights. The current Bishop of Brooklyn is Robert J. Brennan.