The Joffrey Ballet -- returning to the Kennedy Center Opera House Tuesday evening for a week of premiere-packed programs -- is celebrating its 30th birthday.

It's amazing how much dance history the company has packed into three decades. The troupe has changed the face of American ballet as an art form.

From the most modest of beginnings, the Joffrey Ballet has grown to international stature and established a distinct identity that puts it alongside American Ballet Theatre and the New York City Ballet as one of the country's triumvirate of leading classical troupes. With its adventurous repertory -- the Joffrey was the first company to do ballets to rock music, for example -- it drew a new, more youthful, less tradition-bound audience to ballet performances. It led the way in enlisting postmodern choreographers to create work for ballet dancers. And it has become a major repository for 20th-century classics, by such noteworthies as Ashton, Cranko, Fokine, Massine and Jooss.

The man most responsible for all this -- the company's urbane, cheerful 55-year-old founder and artistic director, Robert Joffrey -- looks back on the company's jet-propelled evolution with satisfaction but no complacency. The bumps and brambles on the road to success are too fresh in his memory for that.

"I couldn't help thinking on the way down here," he said on a recent visit occasioned by his membership in the National Council on the Arts, "that our very first company performance took place in a small town not far from here -- Frostburg, in Maryland -- in 1956. The company consisted of all of six dancers then, Gerald Arpino and Glen Tetley among them. It was start of our first national tour."

When Joffrey says they did only one-night stands in those days, he means it literally. The first tour took the dancers to 23 performances in 23 cities and 10 states.

"We traveled in a borrowed station wagon that the dancers drove. The dancers did everything then, including ironing the costumes. And there was often double duty. John Wilson, one of those six dancers, was also our pianist. He'd appear in a tux playing the piano, but he had tights on underneath, so he could dash on stage without a time-consuming change."

Joffrey wasn't with the troupe in Frostburg. He was back in his native Seattle teaching, to make the money that made the touring possible.

"Our second tour, the next year, was a big step up. It was an 18-week tour of one-night stands, covering 69 cities in 25 states -- and Canada. I was always very proud to be able to add that phrase, 'and Canada' -- it made us 'international' even then. We had eight dancers this time, and no one ever missed a performance -- they couldn't afford to. We had essentially one program for the whole tour, with a couple of alternative pieces. I choreographed four of the ballets myself."

Some veterans of that era look back at the period as the "golden days," but Joffrey recalls another side. "The performing conditions were mostly terrible. We had to dance on terrible stages, sometimes with cement floors -- old movie houses, high school gyms and auditoriums. One can say it was marvelous and fun, but no one should have to go through such things again. This was before the tremendous spurt in theater construction in this country, which had nothing comparable to the countless municipal opera houses in Europe.

"And the theater you play in is enormously important. It's not just a matter of having a proper floor, wing space, rehearsal studios, lines for scenery and lighting and so forth. It's atmosphere. The minute you enter the theater the magic should start. You should feel, as you do in the great European houses, that you're about to see something remarkable -- even if, in fact, you don't! That's why we're so pleased, nowadays, to be able to perform in the country's finest theaters regularly -- Kennedy Center, Lincoln Center, and the Music Center in Los Angeles."

The company first appeared in Washington proper in the mid-'60s at Lisner Auditorium. When Wolf Trap opened in 1971, the Joffrey Ballet was one of the summer's principal dance attractions and returned to the site annually for a decade. Since 1974 it has also been seen frequently at the Kennedy Center Opera House -- six seasons out of the past seven.

Washington-bred dancers have also figured prominently in the Joffrey lineup, including Patricia Miller and James Canfield (who have since left the troupe), the first-night principals in the company's production of Cranko's "Romeo and Juliet" during the Opera House engagement two years ago. More recently, Patrick Corbin, formerly of the Washington Ballet, and Bethesda native Roger Plaut have joined the company.

In the company's earlier days, Joffrey himself supplied many of the new ballets, but as the repertoire diversified and Joffrey's administrative responsibilities grew, he was obliged to curtail his choreographic activity. Fortunately, Arpino -- now associate director of the company as well as its resident choreographer -- turned out to have a very prolific imagination, as well as a shrewd eye for the special abilities of individual company dancers. Arpino celebrates his 25th year as a choreographer this year -- indeed, among the Washington premieres on the Kennedy Center programs is his "Birthday Variations," acknowledging the anniversary. The current visit will also include revivals of his "Kettentanz" and "Confetti," as well as performances of his more recent "Light Rain."

Joffrey sometimes misses making his own ballets -- his last was "Postcards" in 1980 -- but finds enormous fulfilment in bringing the work of others to the public. "It's a great reward to see something one has dreamed of actually come to fruition," he says. "For instance, there's Ashton's 'La Fille Mal Garde'e,' which has taken me 10 years to get. Ashton gave us the go-ahead a decade ago, but it's taken that long to arrange the necessary funding and have just the right conditions."

Faith Worth will stage the work for the company, which will present it next year at New York City Center when the company celebrates its 20th-anniversary season there.

Former Royal Ballet principal Alexander Grant, who was a member of the original cast, will also have a hand in the production.

"There's nothing like getting the essence of a ballet from the original dancers," Joffrey says. "They remember things the creator doesn't. They'll tell you things like, 'Oh yes, he said I want this passage against the music, not on the beat,' or 'the line of the arms should be broken here.' The choreographers aren't able to recall such details. Besides, most of them don't like to restage past work. Their whole focus is on the new. They don't want to re-create, they want to create."

Speaking of new work, the company will be presenting four other Washington premieres at the Opera House in addition to the Arpino. Laura Dean (whose own company, Laura Dean Dancers and Musicians, will coincidentally be appearing at the Warner Theatre Friday and Saturday with three premieres of its own) will be represented by her third ballet for the Joffrey troupe -- "Force Field," set to Steve Reich's "Six Pianos." Like the Dean, James Kudelka's "The Heart of the Matter," to Prokofiev's Second Piano Concerto, recently had its world premiere during Joffrey performances at the new Hancher Auditorium in Iowa City, where it was commissioned by the University of Iowa. Kudelka, a Canadian of burgeoning reputation, will also be represented on the Joffrey programs by his "Passage," a 1981 ballet set to a Renaissance motet, "Spem in Alium" ("Hope Above All"), by Thomas Tallis for eight choirs.

Still another Washington premiere will be accorded to Jiri Kylian's "Forgotten Land," set to Benjamin Britten's "Sinfonia da Requiem." Other works on the Joffrey bills at Kennedy Center include "Untitled," the popular Pilobolus collaborative opus; Paul Taylor's "Arden Court"; and Cranko's "Jeu de Cartes." Joffrey, meanwhile, has his sights set on one of the company's most ambitious projects ever -- a reconstruction of Vaslav Nijinsky's original choreography for Stravinsky's "Le Sacre du Printemps," the Paris premiere of which in 1913 set off the most notorious riot in the modern history of the theater.

It was long thought that Nijinsky's choreography -- which received only a handful of performances by the Diaghilev Ballets Russes troupe -- was irrecoverable. But Joffrey, working with Millicent Hodson, a dance scholar who's been researching the subject for years, now hopes actually to mount the ballet in the fall of 1987 in Los Angeles, relying on surviving scores and notations, graphic records, rediscovered costumes and the combined memories of many dancers and ballet masters.

The original "Le Sacre" shook the earth; with Joffrey's push, it could do so once more. Accomplishing the seemingly impossible has been Robert Joffrey's daily task for the past 30 years.