The Okaw Valley Conference was a high school athletic conference in the Illinois High School Association (IHSA), based in Central Illinois. The conference consisted of medium-sized and small high schools. It merged with the Corn Belt Conference to form the Illini Prairie Conference in the 2017-18 school year.
The Okaw Valley Conference was formed in the early 1950s. It originally consisted of Arcola, Arthur, Atwood-Hammond, Bement, Cerro Gordo, Monticello, Newman, Oakland, Sullivan, Tuscola, and Villa Grove. Tolono Unity was added in 1958. In 1971, the smallest seven schools left to form the Little Okaw Valley, and three schools were added: Decatur St Teresa, St Joseph-Ogden, and Warrensburg-Latham. In 1976, Arcola left and Mahomet-Seymour replaced them. In 1982, Sullivan and Warrensburg-Latham left and Argenta-Oreana was added. Tuscola dropped out in 1983. The league folded after the 1984 season.
In 1990 Argenta-Oreana, Clinton, St Teresa, Monticello, Sullivan, and Warrensburg-Latham resurrected the conference, and in 1995, Meridian and Maroa-Forsyth were added. Central A&M joined in 1997, Shelbyville in 1999, and Tuscola and Unity in 2006. The conference was split into two divisions for football in 2006. The Black Division consisted of Clinton, Monticello, Shelbyville, St. Teresa, Sullivan, and Unity. The Blue Division consisted of Argenta-Oreana, Central A&M, Maroa- Forsyth, Meridian, Tuscola, and Warrensburg-Latham. Each team played the five schools from their division, and then four from the other division.
In 2012, 9 teams officially left the Okaw and started a new conference called the Central Illinois Conference (CIC). These schools were Argenta-Oreana, Clinton, St. T, Meridian, Central A&M, Sullivan, Shelbyville, Warrensburg-Latham,and Tuscola. Three teams were left out of the new conference. These teams were Monticello, Tolono, and Maroa-Forsyth. Before the actual forming of the CIC, Argenta-Oreana decided to join the Little Okaw Valley Conference. The Okaw Valley Conference continued with Monticello, Tolono-Unity, Champaign St. Thomas More, St. Joseph-Ogden, and Rantoul.
Maroa-Forsyth High School left the conference for the Sangamo Conference after the 2015-16 school year. In April 2016, school boards of the remaining five schools and the school boards of the five schools in the Corn Belt Conference voted unanimously to merge into a new Illini Prairie Conference beginning in the 2017-18 school year.