Renovation and growth characterized the 1990s, with the renovation of the Lower School Library in 1992, addition of the Tisdall Hall athletic complex and expansion of the Upper School Library in 1993, renovation of the Grace Hall Chapel in 1994, completion of the Campion Center for the Performing Arts in 1995, and modernization of the Aileen Maury Dining Hall in 1997. From modest beginnings, numbering just 17 students, Oak Knoll's current enrollment exceeds 500 students. In 2004, Oak Knoll completed construction of athletic fields, located away in Chatham Township. Athletics The Oak Knoll School Royals compete in the Union County Interscholastic Athletic Conference, which was established following a reorganization of sports leagues in Northern New Jersey by the New Jersey State Interscholastic Athletic Association (NJSIAA). Prior to the NJSIAA's 2009 realignment, the school had participated in the Mountain Valley Conference, which included public and private high schools in Essex County, Somerset County and Union County. With 396 students in grades 10-12, the school was classified by the NJSIAA for the 2019–20 school year as Non-Public A for most athletic competition purposes, which included schools with an enrollment of 381 to 1,454 students in that grade range (equivalent to Group I for public schools). Oak Knoll School offers interscholastic sports for students in grades 5 through 12. For students in grades 9-12, Oak Knoll offers 15 varsity and seven junior varsity competitive programs including: cross country, field hockey, soccer, tennis, volleyball, basketball, indoor track, ice hockey, sailing, fencing, swimming, lacrosse, softball, spring track, and golf. For students in grades 7 and 8, Oak Knoll offers: soccer, field hockey, cross country, basketball, lacrosse and non-competitive tennis. For students in grades 5 and 6 Oak Knoll offers: boys soccer, girls field hockey, boys baseball, Intramural, coed basketball, and non-competitive girls lacrosse. The school was the winner of the 2014-15 ShopRite Cup for Group B, finishing with 113 points, two points ahead of Villa Walsh Academy. The track team won the indoor track Group I state championship in 1982. The fencing team won the overall state team championship in 1984 and 2002. The fencing team won the 2002 state championship with 62 wins and 37 losses in the competition, ten wins ahead of Ramapo High School in second place and 17 wins ahead of Millburn High School in third. The tennis team won the Non-Public Group B state championship in 1987 (defeating Sacred Heart