It happened once again, at the Kennedy Center Opera House last night -- that rare kind of performance miracle that renews one's faith in the power of narrative ballet to transport an audience utterly.

The occasion was the Joffrey Ballet's premiere of the first American production of John Cranko's three-act "Romeo and Juliet," to the celebrated Prokofiev orchestral score. The force behind the achievement was the Joffrey company, and its production, as a whole, but the principal wonder worker was Patricia Miller, the dainty slip of a dancer portraying Juliet. The triumph, moreover, had a none too trivial local cachet about it, since both Miller, and her persuasive Romeo, James Canfield, were luminaries of Mary Day's Washington Ballet before they were recruited for the Joffrey troupe. For both dancers, too, this was a first time out in leading roles in an evening-length ballet.

The magic was late in coming. Until halfway through the scene in Juliet's bedroom that opens the final act, the performance had seemed an admirable, expertly prepared rendering of a generally absorbing story ballet -- not a choreographic masterpiece of the first caliber, but a piece strong enough in theatrical flair to become a popular favorite with ballet audiences for many years. The performance, as I say, had seemed admirable to this point -- but not touching. It was a picturesque, period tale of young lovers and derring-do, but the pathos that suffuses its Shakespearean model was missing, and along with it, any real sense of tragedy.

The delayed arrival of the tragic aura, paradoxically, was due to Miller's interpretation of Juliet, which in the end proved so overpowering. All through the exposition of the drama, from the first glimpse of the heroine in her garden, receiving her first ball dress from Lady Capulet, to the grand ball scene in which she meets Romeo, to the balcony episode in which their budding romance is sealed, to their marriage in Friar Laurence's forest retreat, Miller had played Juliet as a very young girl -- believably a 14-year-old. Juliet was excitable and eager, but neither headstrong nor willful -- rather, a wispy, unaware adolescent.

In Miller's approach to the role, the ripening proceeded ever so gradually, and didn't reach its full depth until doom was clawing at Juliet's heels.

Canfield's Romeo was another story -- the tall, dark and handsome dancer, looking as if born to embody this role, became an adult from the moment of his first sight of Juliet, instantly losing the insouciance of his swashbuckling companions Mercutio (Luis Perez) and Benvolio (David Palmer).

One of Canfield's finest scenes was the one leading up to the fateful duel with Tybalt -- having just wed Juliet, he showed us the tortured Romeo trying desperately to preserve forbearance with her blood kinsman, despite terrible provocations.

The odd imbalance between the depictions of Romeo and Juliet in the earlier scenes kept their romance to a relatively low pitch -- Juliet didn't yet seem up to an all-consuming rapture. Then came the transformation. After her nurse and her parents rebuffed her entreaties in the bedroom scene, and she saw herself condemned to a match with Paris, Juliet suddenly became a woman, and Miller a ballerina. Spreading her shawl like a pair of wings and fleeing to the Friar, sinking to his feet with pleading, Miller the dancer became Miller the artist, and thereafter carried the ballet, through the potion scene and the fake death and the real death which follows, on a tide of poignancy that didn't let up until the final curtain.

Cranko's "Romeo and Juliet" was the work -- in its 1962 staging for the Stuttgart Ballet, which he'd recently taken over as artistic director -- that brought worldwide fame to himself, his company and ballerina Marcia Haydee, his first Juliet. The Stuttgart troupe was the first overseas company to be presented at the Kennedy Center in 1973 -- the year of Cranko's untimely death at 45 -- and "Romeo and Juliet" was its opening attraction.

The Joffrey Ballet realization, as mounted by Stuttgart veteran Georgette Tsinguirdes, splendidly preserves the main virtues of the original, including the swift, compact dramaturgy, the trenchant focus on the lovers and their plight, and the histrionically pointed crowd scenes, for which Cranko had borrowed something of the flamboyance of Leonid Lavrovsky's Soviet version two decades earlier.

Among other highlights of last night's performance were the flashy trio for Romeo and his two companions; the stunning ball scene, its menace so fiercely underlined by Prokofiev's striding measures; the duel scene, in which Jerel Hilding's Tybalt, after a pallid start, took on the requisite malevolence; and the telling finale in the candlelit crypt. Perez's Mercutio, at first shaky and labored, also grew more impressive by the time of his searing swordplay at the close of Act II. Other outstanding portrayals included Charlene Gehm's imperious Lady Capulet, and the three wild Gypsies of the carnival scene -- Leslie Carothers, Julie Janus and Carole Valleskey.

The success of the production, however, is due to a company-wide effort. The wonderfully resourceful, imaginative and dramatically compelling designs of Jurgen Rose (here reproduced from the originals under the supervision of Speed Hopkins) are an important enhancement, as is the strikingly atmospheric lighting by Jennifer Tipton. Conductor Allan Lewis and the Opera House Orchestra provided a lean, clear, aptly sweeping account of the music, though some of the action scenes were driven a bit too edgily for comfort.

There are four more performances of "Romeo and Juliet" to come, starting with tonight's alternate casting of Dawn Caccamo as Juliet and Glenn Edgerton as Romeo, and running through Saturday night. The Joffrey Ballet's most ambitious staging to date, it's well worth a look.