"I'm notorious for being thrown on at the last minute," said Cynthia Harvey. The 22-year-old soloist with American Ballet Theatre had just spent her "day off" rehearsing Kitri, the ballerina role in "Don Quixote," which she performed last night at the Kennedy Center. It was her first performance of the full ballet in Washington -- and her fourth ever -- but ABT fans will remember a couple of seasons back when an injury to Martine van Hamel wreaked havoc with the company's weekend schedule of "Don Q's" and Harvey, then in the corps de ballet, danced the second act of that work -- most of which she had learned the afternoon of the performance. Marianna Tcherkassyky, also a last-minute quick study, danced the other acts. "It was April Fool's Day," Harvey remembers.

Nearly a year later, and with no further rehearsal, disaster again struck and Harvey again stepped in. Halfway through the second act, Cynthia Gregory, who had been dancing Kitri, struck her foot on a wayward barrel as she leaped offstage. Harvey, who had been dancing the role of Mercedes, quickly changed costume and danced on. "After that," said Harvey, "I asked them for a rehearsal. I knew it would happen again."

She got her rehearsals -- two weeks' worth -- and the next time Harvey danced Kitri it was in New York, at the Met. Her Basil was guest Anthony Dowell, premier danseur of Britain's Royal Ballet, who had requested her as his partner. (Last night she danced with Dowell.)

Since then, Harvey had danced several important roles with the company -- her Myrta in "Giselle" has been one of the highlights of ABT's current season. She was scheduled to dance Clara in "The Nutcracker" during the canceled winter season and was asked to do "Swan Lake," again with Dowell, but felt she wouldn't have enough rehearsal time. These roles, for the time being, have been postponed.

Like most "overnight success stories," Harvey has gotten where she is by a combination of hard work, talent and luck. "At ABT, whenever disaster happen, it's whoever is there to take over who gets it."

She was born in San Rafael, Calif., where early tap and baton lessons whetted her dance appetite. At 10, she took a summer ballet class for kids offered by the local YMCA, where the teacher spotted her talent and advised her mother that Harvey should study ballet seriously. For the next six years she studied with Christine Walton at the Novato School. Several summer scholarships to the San Francisco Ballet and School of American Ballet in New York, as well as performances with both local and visiting companies, broadened her experience and cemented her interest in dance.

At 15 she auditioned for ABT's school when the company toured California ("I took class hanging on a door knob so as not to get in the way") and was immediately accepted. The company gave her an academic as well as ballet scholarship -- an unusual step for them -- and Harvey came, alone, to New York. After nine months at the school she auditioned for the company, was made an apprentice, and began being cast in ballets.

She made her debut as a page in the one-act version of "Sleeping Beauty" and bigger roles followed. Her first big pas de deux was in Eliot Feld's "At Midnight," and visiting choreographers, such as Tetley and Tharp, often put her in their ballets.

Her first big break came when Mikhail Baryshnikov staged his "Don Quixote" for the company. Harvey was one of five or six corps de ballet members who volunteered to be the human clay on which Baryshnikov modeled his first choreographic ideas for the ballet. Although told she probably wouldn't get to dance in "Don Q," Harvey was one of the Flower Girls at the ballet's premiere in Washington.

Other dancers besides Baryshnikov have taken an interest in Harvey; she's been "lucky" in that, too. She had danced with Fernando Bujones and been coached in several roles by Natalia Makarova, who has cast Harvey for a leading role in her upcoming, full-length "La Bayadere," now in rehearsal. Kirk Peterson "has been a kind of mentor. He watches my performances and makes a lot of suggestions."

Anthony Dowell has also been important. "He's given me a tremendous amount of confidence. To have had him and me the opportunity to dance with him was such an honor," Harvey said.

"Such encouragement is hardly misplaced. When one watches Harvey dance, one is struck by her classicism -- lovely line, clean technique and fine sense of, style.("Clean, long-limbed and classical -- that's what they always say," say," said Harvey, who hurriedly added, "Not that I mind.") One also notices the evident joy she finds in dancing. "Ballet is hard work," she says, "but it can also be enjoyable. I want to make the audience sense that."

The last time Harvey saved the day in Washington on short notice was last season when Cynthia Gregory was unable to appear on one of Walter Terry's programs of interviews with ballet stars at the Terrance Theatre. It was the day before the start of ABT's spring season, and Harvey was in New York and had planned to come a day early. At 2:30 in the afternoon, as she was leaving for the airport, ABT's director. Lucia Chase, called and asked whether she could appear on the Terry program. After a frantic hunt for music and a suitable costume, Harvey flew to Washington, and five hours later she was on the stage of the Terrace Theatre to dance three strenuous variations in 15 minutes. The works she chose? The Mazurka from "Les Sylphides," the Sapphire Fairy's variation from "Sleeping Beauty," and, of course, Kitri's solo from "Don Quixote."