Olivet Nazarene University (ONU) is a private Nazarene university in Bourbonnais, Illinois. Named for its founding location, Olivet, Illinois, ONU was originally established as a grammar school in east-central Illinois in 1907. In the late 1930s, it moved to the campus in Bourbonnais. The university is affiliated with the Church of the Nazarene and is the annual site of the church's Regional Celebrate Life youth gathering for the Central USA Region.