The school's student body was 68.3% (393) White, 8.5% (49) Native Hawaiian / Pacific Islander, 8.2% (47) two or more races, 5.6% (32) Black, 7.3% (42) Asian and 2.1% (42) Hispanic.

The upper school contains the Chapin Science Complex, the Hockenbury Building (Student Center, Library, and Humanities Classes), Founders Hall (Art, Lunch, and Language, and Dining Hall) and Matthews Theater (music, drama, performing arts etc.)

Today, there are three divisions—Lower, Middle and Upper—located on 208 acres (840,000 m2) which span the Somerset-Morris County line between the Borough of Peapack-Gladstone and Chester Township.

A new athletic center opened in fall 2004 that includes three full-sized basketball courts, administrative offices, and Brueckner Hall.

The school also features five playing fields, a track, seven, tennis courts, an outdoor swimming pool, and a low ropes course.

The Gill St. Bernard's Knights[4] compete in the Skyland Conference which is comprised of public and private high schools in Hunterdon, Somerset and Warren counties and operates under the supervision of the New Jersey State Interscholastic Athletic Association (NJSIAA).

Programs include fencing, basketball, cross country, volleyball, baseball, golf, ice hockey, lacrosse, soccer, softball, track and field, swimming and tennis.

Gill St. Bernard's offers 24 different opportunities for interscholastic sports, including 12 competitive athletic programs for boys and 13 for girls in the Upper School.

[32] The 2007 girls tennis team won the Non-Public Group B state championship, defeating Newark Academy in the semifinals and knocking off runner-up Moorestown Friends School 5-0 in the final match of the playoffs.

[38] In 2016, the team won the Non-Public Group B state championship with a 2–0 win against Hudson Catholic to finish the season 17-4-1.

[44][45] In 2019, the boys basketball team won its fifth straight Somerset County Tournament championship with a 73–53 win against Watchung Hills Regional High School in the finals.