After conquering New York, Warren Leight's Side Man will see on Sept. 16 how it fares in America's Second City. The Tony-winning story of a dying art and a disintegrating family will open the Steppenwolf Theatre Company's 1999-2000 mainstage season.

Company members Rick Snyder and Rondi Reed will play Gene and Terry, the story's side man trumpet player and his long-suffering wife, while Garret Dillahunt play their peace-making son, Clifford. Anna D. Shapiro directs.

Side Man won the 1999 Tony Award as best play, also nabbing a Tony for actor Frank Wood. The production is expected to end its run on Broadway on Oct. 31, and then begin a run at the Kennedy Center's Eisenhower Theater, Nov. 3-28. Andrew McCarthy and Tony-winner Frank Wood are set to star in the DC mounting.

Side Man will officially open at Steppenwolf on Sept. 26, for a run through Nov. 7.

* The Steppenwolf mainstage season runs as follows:

• Hysteria (Nov. 26,1999-Jan. 22, 2000, opening Dec. 5), Terry Johnson's comedy about Sigmund Freud's last days in England, in 1939, directed by John Malkovich.

• Marber's Closer (Feb. 3-March 26, 2000, opening Feb. 13), with Abagail Deser directing. Closer's quartet of dysfunctional romantic partners were originally played on Broadway by Natasha Richardson, Anna Friel, Rubert Graves and Ciaran Hinds, under Marber's direction.

• Gary Sinise will star as McMurphy and Amy Morton as Nurse Ratched in Dale Wasserman's adaptation of Ken Kesey's One Flew Over the Cuckoo's Nest, (April 6-June 4, 2000, opening April 16). Terry Kinney will direct. Sinise and Kinney are co-founders of Steppenwolf. The show will be presented at Steppenwolf by arrangement with Michael Leavitt and Fox Theatricals. As for a possible transfer to Broadway in the 2000-01 season, a production spokesperson told PBOL (March 25), "It's our hope that will happen; Fox Theatricals owns the New York rights, and that's why we're with them."

• Valparaiso (July 6-Aug. 27, 2000, opening July 16), Don DeLillo's exploration of one man's ordinary business trip to Valparaiso, IN., directed by Frank Galati. In Valparaiso, which premiered earlier this year at MA's A.R.T., a man who took the wrong plane to a mysterious destination now finds himself the obsessive focus of interviews and talk shows. With Valparaiso, world-renowned novelist DeLillo ("White Noise," "Libra" and "Underworld") made his second venture into the theater world. His first play, The Dayroom, premiered at the A.R.T. in 1986. The novel "Libra," about Lee Harvey Oswald, was adapted into a play by Malkovich and produced by Steppenwolf in 1994.

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The 1999-2000 season at Steppenwolf's Studio Space runs as follows:

• Her Name Was Danger (Nov. 17-Dec. 12), a Lookinglass Theatre Steppenwolf co- production, created and directed by David Catlin.

• The Infidel, by Bruce Norris (Feb. 24-March 26, 2000), directed by Anna D. Shapiro.

• Redmoon's Hunchback (May 17-June 11, 2000), a Redmoon Theater-Steppenwolf co production, by Jim Lasko, based on Victor Hugo's novel, music by Michael Zerang.

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The 1999-2000 Steppenwolf Garages season runs as follows:

• Kenneth Lonergan's This Is Our Youth (Oct. 14-Nov. 14), in collaboration with Roadworks Productions.

• Austin Pendleton's Orson's Shadow (Jan. 13-Feb. 13, 2000); Orson Welles, Laurence Oliver, Vivien Leigh, Joan Plowright and Kenneth Tynan are the quintet featured in actor-director-dramatist Austin Pendleton's latest work.

--By Robert Simonson