Robert Joffrey is 55 years old now, and the company he founded and directs celebrates its 30th anniversary this year. Even so, youthfulness remains the Joffrey Ballet's most constant and conspicuous trait, as the troupe demonstrated anew on the Kennedy Center Opera House stage last night at the start of a week of performances.

This was made more obvious than usual by an opening night program that for the most part emphasized surface values -- speed, vivacity, sexual allure, boundless energy and sleek physical prowess. These have always been prominent features of the Joffrey's appeal, and indeed, they are basic to the attraction of the art form. Don't we all go the ballet to pretend vicariously that we too can leap and spin effortlessly, and dazzle with our beauty?

In the case of the Joffrey Ballet, such qualities are as much fact as artistic illusion. Ballerina Denise Jackson, a youthful-looking dancer still, has been with the troupe for 17 years, but she's more the exception -- most of the present company was enlisted within the past five years. To be sure, youth is a state of mind. But the state of Joffrey's mind is young, and this is reflected not just in his company's consistently fresh approach.

The one ballet of the evening that wasn't on the superficial side was James Kudelka's "Passage," a 12-minute work for six dancers set to the Thomas Tallis motet "Spem in Alium" ("Hope Above All") for eight a cappella choirs. Seen here in its Washington premiere (it was created for ABT II in 1981), it's a work that seems deeper in overall impression than any of its elements can singly account for. This is a tribute to the gifts of 30-year-old Kudelka, still a relative newcomer to choreography.

The movement vocabulary Kudelka employs in "Passage," melding classical and modern motifs, isn't very different from what one sees in the work of continental ballet choreographers, including Cranko and Jiri Kylian (the latter also represented on this Joffrey program). The distinctiveness of "Passage" lies in how he uses these movements to achieve a genuine sense of mystery and solemnity. It's true that the ethereal Renaissance piety of Tallis' music goes a long way toward evoking such responses all by itself. But if the choreography were the least bit inauthentic in feeling, it would be instantly grating, and this never happens. The ballet opens on a darkened stage, revealing the lone, whitened form of a man (David Palmer) clad only in headband and white briefs. As the shimmering choral sound casts its spell, and the other dancers gradually wander in, somberly attired, it becomes clear that Palmer is a sort of Christ figure. When he approaches the others individually, they seem to be in bent or sagging postures of pain or despair. He lends them support and consolation, but he stands ever apart from the rest. Toward the end, it's he who seems despairing, alone and groping on the floor. Then it's the others' turn to raise him up -- in a Pieta image -- and offer him succor. At the last, they drift off, leaving him reaching after them in a gesture of tenderness and gratitude.

The cast, which also included Carole Valleskey, Mark Goldweber, Philip Jerry, Beatriz Rodriguez and Denise Jackson, demonstrated that youthfulness is no bar to sensitivity, and Palmer's affecting, carefully weighted performance counted for much in the total effect.

The evening's other Washington premiere was of Kylian's "Forgotten Land," first performed by the Stuttgart Ballet in 1981 and set to Benjamin Britten's "Sinfonia da Requiem." Outwardly, it's no less serious a ballet than "Passage," with its abstract set like an angry sky and its surging ensemble of 12 dancers swirling in impassioned tides across the stage. Ultimately, though, the ballet seems more a matter of mannerism than substance -- a skillfully wrought exercise in synthetic poignancy. It was, however, splendidly danced.

The other two ballets were samplings from resident Joffrey choreographer Gerald Arpino's large stock of euphoric crowd-pleasers -- the exotically tinged "Light Rain," and a revival of the ebullient, aptly titled "Confetti." It was here that youth had a field day, and then some. Dawn Caccamo's stylish verve was outstanding in "Confetti," and Leslie Carothers and Philip Jerry were the effectively slinky lead couple in "Light Rain."