The Ridgefield Park High School Scarlets 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 (NJISAA). Prior to the 2010 realignment, the school had competed in the Bergen County Scholastic League (BCSL) American Conference, which included public and private high schools located in Bergen and Hudson counties. With 667 students in grades 10-12, the school was classified by the NJSIAA for the 2019–20 school year as Group IV for most athletic competition purposes, which included schools with an enrollment of 486 to 758 students in that grade range. The football team competes in the American Red division of the North Jersey Super Football Conference, which includes 112 schools competing in 20 divisions, making it the nation's biggest football-only high school sports league. The school was classified by the NJSIAA as Group II North for football for 2018–2020.