Now known as iO Chicago, the group formerly known as the Improv Olympic Theatre was founded by Charna Halpern and Del Close in 1981. The style of iO is longer form improv, and the group has trained over 5,000 people. Some of the more recognized graduates include Chris Farley, Tina Fey and Mike Myers.
Halpern and Close co-wrote the book Truth in Comedy, The Manual for Improvisation.
There is a west coast affiliate of the same organization called iO West in Los Angeles.
