Spring ensemble member Alexandra Socha – who currently understudies Lea Michele, the show's original Wendla – will graduate to that role. Groff and Michele both exit the award-winning musical May 18; Socha will begin performances May 20, and Riabko will join the cast May 23.

Riabko will be making his Broadway debut in Spring Awakening. His debut solo recording, "Before I Speak," is available on the Columbia Records label. The singer has also toured with Maroon 5 and John Mayer.

Prior to her Broadway debut with Spring Awakening, Socha appeared at the American Stage Festival and the Lyric Stage.

The Spring Awakening company also features Blake Bashoff (Moritz), Skylar Astin (Georg), Lilli Cooper (Martha), Blake Daniel (Ernst), Brian Charles Johnson (Otto), Emma Hunton (Ilse), Phoebe Strole (Anna), Matt Doyle (Hanschen), Remy Zaken (Thea), Christine Estabrook (Adult Women), Glenn Fleshler (Adult Men), Gerard Canonico, Alice Lee, Eryn Murman and Matt Shingledecker.

Based on the 1891 play by Frank Wedekind, Spring Awakening won eight 2007 Tony Awards, including Best Musical. The production features direction by Michael Mayer, choreography by Bill T. Jones, book and lyrics by Steven Sater and a score by Duncan Sheik. Spring Awakening launches a national tour at San Francisco's Curran Theatre Sept. 4-Oct. 12. Prior to officially hitting the road, Spring Awakening will rock San Diego's Balboa Theatre Aug. 15-31. Casting for the tour will be announced shortly.

Songs featured in the Tony-winning score are "All That's Known," "And Then There Were None," "Blue Wind/Don't Do Sadness," "Left Behind," "Mamma Who Bore Me," "My Junk, "The Bitch of Living," "The Dark I Know Well," "The Guilty Ones," "The Song of Purple Summer," "The Word of Your Body," "Those You've Known," "Totally Fucked," "Touch Me," "Whispering" and "The Mirror-Blue Night."

The musical made its world premiere Off-Broadway at the Atlantic Theater Company in June 2006. Spring Awakening transferred to Broadway the following November, where it continues to play at the Eugene O'Neill Theatre.

For tickets call (212) 239-6200 or visit www.telecharge.com.