In Ensemble X's April Fool's Day concert, all is not as it seems. Coded messages, double meanings, pandemonium and musical mishaps abound.

The free concert, Saturday, April 1, at 8 p.m. in Barnes Hall on campus, is the new-music ensemble's swan song. Steven Stucky, the Given Foundation Professor of Music at Cornell and artistic director and conductor of Ensemble X, is disbanding the nine-year-old group, composed of faculty musicians from Cornell and Ithaca College. A party will be held on the stage following the performance.

Stucky was considerably busy even before he won the Pulitzer Prize in 2005 for his Second Concerto for Orchestra. But his growing list of commitments -- commissions, guest appearances, his work as the Los Angeles Philharmonic's consulting composer for new music and host of the New York Philharmonic's "Hear & Now" series -- have led to his decision to declare Ensemble X a rousing success -- and walk away.

The all-Viennese program for the ensemble's farewell performance, "Mit Schlag," includes Mozart's comical "Ein musikalischer Spass" (or "A Musical Joke"), a parody of ham-fisted composers and rustic musicians; Alban Berg's "Lyric Suite" (featuring soprano Judith Kellock and Ithaca College's Ariadne String Quartet), a string-quartet staple that encrypts a secret love affair in its text; and ghouls and superheroes parading through the Kurt Weill-meets-Spike Jones cabaret of H.K. Gruber's "Frankenstein!!" Based on macabre children's rhymes by J.C. Artmann, "Frankenstein!!" will feature chansonnier Scott Tucker and an ensemble of 12 musicians led by Cynthia Johnston Turner.

Since its first concert in November 1997, Ensemble X has performed more than 130 different works, many of them world and regional premieres; given more than 30 concerts and released two CDs. The group also performed two concerts in New York City, and a small group of its players have toured the Southeast.

"We have built a loyal following among music lovers in Ithaca and a surprisingly widespread reputation elsewhere," Stucky said.

In addition to the Pulitzer, Stucky received the Medal of the Witold Lutoslawski Society in 2005; and Chamber Music America's "101 Great American Ensemble Works," announced in January 2005, included his 2000 composition "Nell'ombra, nella luce" ("In Shadow, in Light"). His other awards include the American Society of Composers, Authors and Publishers (ASCAP) Deems Taylor Prize for his 1981 book "Lutoslawski and His Music," a Guggenheim Fellowship in 1986 and a Bogliasco Fellowship in 1997.