The New York Youth Symphony is the kind of invaluable organization that was plentiful in the 1950's and 60's, but seems anomalous today, when young people supposedly have no interest in classical music. Yet this ensemble, which was founded in 1963, seems not to lack participants. It has a roster of 185 musicians, ages 12 to 22, half from public schools, who rehearse and perform full-fledged repertory works, from Beethoven to Stravinsky, as well as new scores commissioned for them.

The composers who write for these players don't skimp on modernist difficulties. The premiere on the orchestra's Sunday afternoon program at Carnegie Hall, Ryan Anthony Francis's "Axiom" (2005), has its share of difficult turns, including a shifting texture that must move, quickly but subtly, from cloudy and shimmering to focused and rhythmically sharp-edged. Paul Haas, the orchestra's music director, had his players focused fully on the work's challenges, and the performance proved an appealing showcase for Mr. Francis, who was born in 1981 and is likely to be heard from again.

Just before Mr. Francis's work, Mr. Haas opened the program with Leonard Bernstein's "Candide" Overture. As curtain-raisers go, it is difficult to beat "Candide," with its glittering textures and ebullient rhythms, but those qualities make considerable demands in both energy and cohesion. If there is one thing young musicians can be counted on to provide, though, it is energy, and these players gave the overture a zesty and beautifully polished reading.

The program also included two works from the core repertory. On the first half, Carter Brey, the principal cellist of the New York Philharmonic, joined Mr. Haas and company as the soloist in a shapely, singing account of Dvorak's Cello Concerto. And after the intermission, the orchestra offered a solid and often electric performance of the Beethoven Fifth Symphony.