Two years in the planning, the Youth Orchestra of the Americas — 120 musicians mostly between the ages of 15 and 25 and mostly (3/4) from Latin America — made its debut last Thursday in Jordan Hall under the baton of Benjamin Zander; and like their American counterparts at the New England Conservatory, these kids showed they can play grown-up programs — in this case Beethoven’s Fourth Piano Concerto and Mahler’s First Symphony — with the grown-ups. The YOA’s tour schedule encompasses 11 concerts in seven countries, including a performance of the Dvorák Cello Concerto with Yo-Yo Ma at Wolf Trap. But it’s not too soon to call this high-profile project a success.

The Jordan Hall program opened with the world premiere of the YOA- commissioned Voices Rising (Anthem of the Americas). New York Philharmonic associate principal bass Jon Deak took what he describes as "thematic and rhythmic fragments written by 15 rising young professional composers representing 11 countries of the Americas" and created a paratactic cacophony — think traffic jam — that’s halted only by a frustrated outburst from the timpani, after which a cello theme (from a 12-year-old!) that wouldn’t discredit Vaughan Williams rises and the orchestra discovers syntax, not to mention swingy rhythms. All in just six minutes, but it deserved to be longer.

With its sober, almost melancholy dialogue between piano and orchestra, Beethoven’s G-major concerto makes demands that go beyond prestidigitational pyrotechnics. Seventeen-year-old Horacio Levandera, from Buenos Aires, might have looked the virtuoso with his long hair and cherubic visage, but his opening chords proved he could speak quietly and eloquently, and the orchestra (reduced to 55 or so) proved it knew how to listen. Levandera has technique and tone and (almost) temperament — at times I wanted less artistic maturity and more artistic personality, à la Wilhelm Kempff. Maybe that goes back to technique: he plays from the elbows, or even the wrists. The fireworks were reserved for his encore, Alberto Ginastera’s Danza del gaucho matrero.

The orchestra got a chance to show off its own artistry in the Mahler First, and it responded with an awed, misterioso reading of the cicada-buzz opening bars. Zander wasted no time declaring his intentions: the clarinet fanfares beginning at bar 9 were taken piú mosso, as Mahler asks, but not rushed, as is usually the case; and throughout the conductor gave Mahler’s song and dance full value, saving the dramatics for the drama. The Scherzo’s café-schmaltz trio had sentiment without sentimentality; the "linden tree" flashback that interrupts the funeral march bloomed more radiantly than on any of my 50-odd recordings at home. And though the 1992 International Gustav Mahler Society Critical Edition calls for all the basses to play at the outset of the funeral march (how come Bruno Walter didn’t know about this?), Zander stayed with the traditional solo, which was affectingly executed. There were the usual youth-orchestra bloopers, fewer than you might expect for the first performance out of the box; more important, the playing was good enough to permit Zander to realize his lyric/dramatic view of the symphony. Two kinetic encores, Oscar Lorenzo Fernández’s samba-inflected Batuque and the Mambo from West Side Story, showed the YOA can shake a leg as well.