The June 27 evening will feature the Tony-winning Avenue Q score performed in jazz, classical and "other surprising arrangements." Mary Ann McSweeney, who plays bass in the Avenue Q orchestra, will be the musical director for the 7:30 PM concert, which will boast a host of special guest stars to be announced at a later date.

The one-night-only event will help raise funds to replace two of the well-worn Steinway grand pianos at the Greenwich House Music School. Avenue Q's Lopez studied at the school for over 15 years, and he and Marx composed much of the Q score at the school where they noticed the need to replace the 50-year-old instruments.

Robert Lopez and Jeff Marx met at the BMI Workshop in 1998. Prior to Avenue Q, they collaborated on Kermit, Prince of Denmark and Theatreworks/USA's Reading Rainbow and Ferdinand the Bull. The young composers/lyricists are currently at work on a musical comedy film for Universal Pictures as well as a stage musical with "South Park" creators Matt Stone and Trey Parker. Avenue Q, which continues to play to sold-out audiences at the Golden Theatre, is expected to open at Wynn Las Vegas in September 2005.

The Lucille Lortel Theatre is located in Manhattan at 121 Christopher Street. Tickets, priced $75, $150 and $250, will go on sale June 1 by calling (212) 279-4200 or by visiting www.ticketcentral.com.

* Greenwich House Music School was founded in 1905 and provides affordable music lessons and musical events for all ages.