The Private Schools Athletic Association (PSAA) was formed in 1917 to fill a need for a secondary school sports league for the private schools in the New York metropolitan area. Prior to the 1920s, New York City had the longest history with private schools leagues, beginning with the New York Interscholastic Athletic Association formed in 1879. This league went into decline and disappeared in the first decade of the twentieth century, leaving the city without a private league.
During World War I, the private schools felt the need of a league, and got together for a track and field meet in the spring of 1917. Prominent members were Polytechnic Prep, Horace Mann, Dwight, and Trinity. New York’s Catholic schools during much of the 1920s did not have much league sponsorship, and also participated in league events, notably DelaSalle, Bishop Loughlin, Augustine, and LaSalle Military Academy.
The PSAA league gradually expanded into other sports, adding cross country in 1921, fencing and basketball in 1926, and swimming in 1927, to become a full-fledge league by the end of the 1920s.