The iO improv troupe was founded in 1981 by the late, great, and inexplicably unsung Del Close, an improv pioneer who branched off from his more mainstream counterparts at Second City to pursue an unorthodox methodology (the letters "iO" stand for "ImprovOlympic," the group's original name). A legendary iconoclast, the colorful Close developed a long-form improv technique known as "The Harold." It eschewed the traditional sketch format in favor of more conceptual comedy scenes: The audience suggests a theme for the evening, then a series of skits, monologues, and songs are built around it. Second City, whose vignette-blackout-vignette format had grown weary, has since co-opted the method. iO offers a nightclub setting for a variety of unscripted nightly performances, from free-form pieces to shows loosely based on concepts such as Star Trek or dating. Like all improv, it's a gamble: It could be a big laugh, or the amateur performers could go down in flames. Monday is an off night for most other clubs in town, and iO takes advantage with a show called the Armando Diaz Experience, an all-star improv night that teams up some of the best improvisers in Chicago, from Second City and elsewhere. Besides Mike Myers, successful alums include Tim Meadows, Andy Dick, Amy Poehler, and the late Chris Farley.

Copyright: Excerpted from Frommer's Chicago 2009, (c) 2008, Wiley Publishing, Inc.

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