A lot of print has been expended on the story Tharp is trying to tell here-the story of Eddie and Brenda and Tony and Judy and James, pals back in high school, whose lives are shattered by Vietnam and then, slowly, repaired-except for James, who is killed in battle at the end of Act I. (He makes a comeback appearance in a visionary scene in Act II, and a good thing too, considering how compelling Benjamin G. Bowman is both as a decent young kid and a dying grunt.) For the record: Eddie and Brenda break up, Brenda and Tony fool around, James and Judy get married (there's a wonderful touch when he gets down on one knee to propose and one of his hands flutters for a moment against his heart), Vietnam, postwar degradation-dope, orgies, panhandling, disco -and finally healing and reconciliation, with Tony and Brenda back together and friends reunited.

I call this a story, but it isn't one, actually, and it certainly isn't a plot; it's a series of generic situations linked by the sensibility and sound of Billy Joel's songs and the fecundity of Tharp's dance language. The dances don't illustrate the songs as much as embody them-and, at times, leave them behind. Yet the songs give Tharp a chance not only to return to her lifelong obsession with American youth as expressed in the way it dances and moves, but also to extend her range into war, death and regeneration. The initial Vietnam sequence is harrowingly effective, all tracer bullets and explosions, bravado and terror; no one has done this better. The orgy scene is much less original; it seems to be just going through the motions (which include shooting up, humping and the odd whip).

The more storylike moments of renewal-Judy and Eddie run into each other while jogging, everyone gets together at a reunion in the final scene-are far less convincing than what is the real climax of Movin' Out , a tremendous outburst of joyous dance energy from Eddie and the ensemble to "River of Dreams," "Keeping the Faith" and "Only the Good Die Young." From the opening words-"In the middle of the night"-this number blasts the theater apart, not only through its daredevil lifts and throws and slides, the nonstop propulsive excitement of all these terrific dancers going all-out, but because Tharp makes us accept that in her world-and, for the moment, in ours-what really heals is dance itself. The jogging, the reunion, the hugs, the uncorked bottle of champagne-these are sentimental clichés that are Tharp's accommodations to the genre she's embracing, the Broadway show.

She goes really wrong only once, when she has Judy-in an ugly black dress with little slits in it and an even uglier hairdo-bourréeing and jetéing through the Vietnam vision scene while tormented soldiers convulse around her. This is not only mawkish and pretentious, it's the one place where the marriage of Tharp's modern-dance vocabulary and classical-ballet vocabulary fails to work: The two styles fight each other, and ballet loses. Judy's trajectory from official Nice Young Girl to tragic emblem-that is, we might say, from jitterbugger to ballerina-isn't earned; I suspect it has to do with the casting of Ashley Tuttle, a core member of Tharp's regular company, who happens to be an exquisite classical dancer (she's a principal at American Ballet Theatre-an exemplary Giselle). You can put Tuttle in a cute teenage outfit and have her hanging out with the local grease monkeys, but the Giselle comes through; beneath the hip-hop, her movement is irredeemably refined.

You can also spot the classicist beneath the prole in the performance of the two lead men, John Selya as Eddie and Keith Roberts as Tony. Both are refugees from A.B.T., and both are the beneficiaries of Tharp's unerring intuition about what a dancer's strengths may be-in this, she does resemble Balanchine. In the last several years, she's revealed these two as tremendous technicians and profound interpreters of her kind of dance. The same is true of her leading woman, Elizabeth Parkinson, a red-haired beauty who can be both dominating and lyrical, as required. These three are so powerful, so secure, so convincing as they toss off the wickedly demanding feats Tharp requires of them that you wholly accept them as the characters they're meant to be portraying.

And yet when you watch the alternate dancers who perform the leading roles at matinees, something interesting happens to the show. They don't have the total dance authority of the first cast, and that may be why they seem closer to the actual world of Billy Joel-you can imagine them emerging from a youth of broken-down convertibles, cheerleaders, jukeboxes, acne. William Marrié, the brilliant substitute for John Selya, is a little less convincing as a dancer and a little more convincing as an Eddie. Karine Bageot (Alvin Ailey, The Lion King , currently on the screen in Frida ) softens Brenda-she's all smiles and sex appeal-whereas Parkinson is as spiky, as tough and as demanding as … Twyla Tharp herself. Ron DeJesus, the substitute Tony and another first-rate dancer, could have come out of the projects, while Keith Roberts, with his all-American good looks and impeccable technique, could only have come out of ballet school. So although it would be a serious loss to miss Selya, Roberts, Parkinson and Tuttle (luckily, Bowman plays every James), don't feel cheated if you find yourself at a matinee. And in one regard, you'll definitely come out ahead: good as Michael Cavanaugh is as the piano-and-song man in charge of the music side of things, Wade Preston is better-the voice is deeper, more emotionally charged, more affecting. He even looks more like Billy Joel.

Movin' Out , then, is a landmark Broadway event, though it may also prove to be a dead end. There are no other Twyla Tharps out there-just compare her work to, say, Susan Stroman's in the insanely overpraised Contact , which serves up one cliché after another without mercy or remission. Tharp's only competition is her friend and onetime collaborator, the late Jerome Robbins (years ago, they made a piece together, Brahms/Handel Variations , for City Ballet.) Like Robbins, Tharp has large, ambitious concepts; and like him, she's not only an obsessive worker but a tyrant, demanding the best out of everyone, starting with herself, and usually getting it. You could say that Movin' Out is the first real successor to West Side Story , although that show had the advantage of a clear and powerful storyline- Romeo and Juliet , remember? But watching this new show, I thought of Robbins more specifically in relation to his Dances at a Gathering . There's a famous moment at the end of that ballet when the central male dancer-Edward Villella, originally-bends down and reverently touches the floor, which is where all dancing begins. Towards the end of Movin' Out , Tharp-in homage? going Robbins one better?-has Keith Roberts bend down and seem to kiss the floor. I guess the stakes are higher these days. But then, with Twyla Tharp, the stakes are always high. Like all real artists, she's a gambler, and this time she's hit the jackpot.

When she began, the battle between "ballet" and "modern dance" was still raging. Who would have predicted that this battle would be neither won nor lost, but that the two factions would slowly merge? (Israelis and Arabs, please take note.) More than anyone else, Twyla Tharp is responsible for this hybridization: Her loyalty to her stubbornly individual modernisms runs parallel to her lifelong love affair with ballet. In Push these two impulses operated separately, in opposition or at least in humorous contradiction, which may be why the ballet looks a little dated today; the joke is no longer relevant. Working for ballet companies around the world, Ms. Tharp has striven to absorb the classical language into her own language, recognizing, perhaps, that personal styles, however effective, die with their creators, but that classicism survives.

Now, a quarter of a century after Push , she has formed a new company, found a "permanent" home in Brooklyn and announced an agenda that would paralyze any other 60-year-old artist: She wants to revive (and film) many of her earlier works, grow her company from its current six members to 12 and then 24, and start adding 20th-century works by other choreographers to what she plans to call the Brooklyn Ballet. And maybe she can do it. Who else has the guts and the know-how and the self-confidence to attempt the rescue of a century of dance?

Her new company, Twyla Tharp Dance, recently made its first New York appearance a mere week at the Joyce, presenting two works she choreographed last year. First came Mozart Clarinet Quintet K581 a quintessentially Balanchinian title, although he might have thought twice about including the Koechel listing. All five of its dancers come from ballet Ashley Tuttle, a current principal at A.B.T.; Keith Roberts and John Selya, ex-members; Benjamin Bowman, ex City Ballet; and Elizabeth Parkinson of Joffrey, Feld, etc., and more recently (with Mr. Roberts) of Broadway's Fosse . Unsurprisingly, then, this work is very ballet-inflected: You can only wonder why the girls aren't on pointe. As befits its Mozartean inspiration, it has its courtly accents (the occasional bow or kissed hand), an elegance that sits edgily but not uneasily with the echt Tharp vocabulary of sudden twists and darts, little shoulder wriggles and head thrusts, but its raison d'être seems to lie in solving complicated partnering issues. (If Ms. Tuttle isn't upside down, she's being tossed from one guy to another.) There isn't a stupid or vulgar moment in it, but to me it's less a deep response to Mozart's quintet than a lesson in technique which Ms. Tharp is administering to herself: This is one of those moments that makes me feel that ballet is in her head, not in her blood. Perhaps because she's so busy working things out, Mozart's heart doesn't seem to have touched hers. She herself has said that sometimes she starts choreographing to one piece of music, then switches to another; in other words, the dance is linked to the music but not born of it. Twyla Tharp is not going to take orders from anyone, not even Mozart!

But what she gets out of her dancers! And how interestingly contrasted they are, Ms. Tuttle and Mr. Roberts looking more like ballet dancers deeply invested in Tharp, and Ms. Parkinson and Mr. Selya looking more like Tharp dancers deeply invested in ballet. (Synthesis can take you only so far.) Indeed, the second new piece, Surfer at the River Styx , identifies Mr. Selya as an ultimate Tharpian much as I admired him in his A.B.T. days, I wasn't prepared for this explosive, nuanced, thrilling performance. He may have been a corps member at A.B.T., but at Twyla Tharp Dance, he's a star. In Surfer , he's in pale loose garments, making his tortured way across a darkened stage to music, or sounds, by Donald Knaack that suggest everyday noises subway trains roaring into stations, clanging bells. Mr. Bowman and the women of the Mozart piece have been joined by Alexander Brady (from Miami City Ballet), and these four, in black, are chorus, observer, obstacle to Mr. Selya's progress, presumably across the Styx into the next life. Mr. Roberts, also in pale garb, is the challenger, the anti-Selya and indeed at one point the two men are actually boxing. (Ms. Tharp relishes a good fight.) With Push , Twyla Tharp opened up new territory for Mikhail Baryshnikov, indisputably the world's greatest dancer. On a more modest scale she accomplishes the same thing here, identifying the strengths and liberating the energies of her entire troupe.

In recent interviews, Ms. Tharp has revealed that Surfer was suggested to her by Euripides' The Bacchae : She alludes to the cult of Dionysus and the Eleusinian mysteries, and she's told Robert Johnson in the Newark Star-Ledger that the dance contains an "'all-purpose Chaos and explosion of the Earth' ultimately Surfer at the River Styx is about humility and compassion for human feelings." (I'll take their word for it, although humility is not the first quality I associate with Twyla Tharp.) This kind of programmatic thinking may help Ms. Tharp formulate her concepts and even realize them, but I don't know that it's of much use to the viewer. What we see on stage is an exciting if dark rave-up, with two superb male dancers going all-out to display their bravura powers. Mr. Roberts does endless pirouettes, as intense as they are accurate, and Mr. Selya steals the show with his passionate hip-hoppy routine as he slides and whirls and shudders across the stage in an extended solo that assures the success of this continuously interesting work. That it ends in a kind of apotheosis, with the beautiful Ms. Parkinson held aloft, bathed in a transfiguring glow, presumably indicates that Mr. Selya has made it over the Styx to the promised afterlife. What it inescapably looks like, however, is the close of Balanchine's Serenade , which is enough of an afterlife for me. It should come as no surprise that Ms. Tharp should end a piece with such a tribute: Balanchine has always been an inspiration for her. I only wish she could absorb more deeply the lesson of his relationship to music.

Meanwhile, the winter season of Balanchine's own City Ballet wound down way down with its third premiere, Peter Martins' Burleske , set to the famous Richard Strauss score. It's yet another ballroom ballet (though alas nowhere near the level of La Valse or Liebeslieder Walzer or Vienna Waltzes) , prettily costumed by Carole Divet in a kind of homage to the great Karinska but that's the only way it suggests the glories of the past. Five corps couples and two lead couples keep rushing on and off. Darci Kistler is partnered by Jared Angle, and once again Mr. Martins (her husband) has carefully protected her from unrealistic demands. She has some quick turns, and it's good to see that she can pull them off, but she doesn't do much else, and none of it is telling. Janie Taylor is actually asked to dance, and she reveals her clear allegro attack while being graciously partnered by Peter Boal, but again to no point. Or maybe a point is intended: Ms. Kistler and Mr. Boal are elder statesmen (statespersons?) of the company, Ms. Taylor and Mr. Angle its newest soloists. At the end of Burleske , in a totally undramatic plot twist, the couples switch: The youngsters go off together, and the elders are left alone on stage. Is this meant to be a ballet about one generation of dancers replacing another? It hardly matters. The whole thing is so bland, so empty, that even The New York Times turned thumbs down.