[13] There is a wide range of activities and clubs for students to participate in:[14] The Westwood Regional High School Cardinals[3] compete in the Big North Conference, which is comprised of public and private high schools in Bergen and Passaic counties, and was established following a reorganization of sports leagues in Northern New Jersey by the New Jersey State Interscholastic Athletic Association (NJSIAA).

River Dell also hosts a co-op ice hockey team that includes Emerson Junior-Senior High School and Westwood.

[25] The field hockey team won the North I Group II state sectional title in 1987 and won the Group II state title that year as co-champion after a 1–1 tie in the finals against Moorestown High School to finish the season with a record of 18-2-1.

[31] The 2000 team won the North II Group I state sectional title with a 33–7 win against Pompton Lakes High School in the championship final played at Kean University.

[32] The 2006 team went to Giants Stadium in East Rutherford where they played the Indians of Pascack Valley High School in the North I Group II finals, beating them 9–8.

[34] The team won the North I Group II sectional title in 2022, stopping a two-point conversion by Rutherford High School with seconds left on the clock to win 21-20[35] and repeated in 2023 with a 20-7 victory in the North I Group II sectional finals against Rutherford.

[30] The boys' spring track team won three consecutive Bergen County Tournament championships from 2004 to 2006.

In Spring 2005 the team went undefeated in Bergen County, and won the North I Group II state championship by a record margin.