The Illinois High School Association, founded in 1900, is a not-for-profit organization of over 750 public and private high schools. The IHSA is governed by a eleven-member Board of Directors, who are principals of member schools. One member, the treasurer, is appointed by the Board and does not vote.

Through its administrative staff of one executive director and eight assistant executive directors, the IHSA regulates interscholastic competition in 13 sports for boys and 13 sports for girls, as well as 7 non-athletic activities. The IHSA stages state final events in all of these sports and activities except music.

The IHSA is a charter member of the National Federation of State High School Associations, a group of 51 state associations. The IHSA Offices are located in Bloomington, Illinois.