Delbarton School is a private, all-male Catholic college-preparatory school in Morristown, New Jersey, serving students in seventh through twelfth grades. It is independently directed by the Benedictine monks of St. Mary's Abbey in Morristown and is located in the Diocese of Paterson.

As of the 2023–24 school year, the school had an enrollment of 646 students and 83.4 classroom teachers (on an FTE basis), for a student–teacher ratio of 7.7:1. Delbarton's student body comprises students from more than eight New Jersey counties and 100 communities.

Delbarton is a member of the New Jersey Association of Independent Schools and has been accredited by the Middle States Association of Colleges and Schools Commission on Elementary and Secondary Schools since 1961.

The school offers financial aid to families who cannot afford the cost of tuition, and financial aid offers are considered independently of admission. Annual tuition is $48,725 for the 2025–26 school year. Delbarton is a host site for NJ Seeds' young scholars program where every summer academically qualified but economically disadvantaged students attend classes on the Delbarton campus.