"This is such a terribly frustrating profession," says Alvin Ailey. "It's a high-anxiety business. Dancing is either right or wrong, there's no in-between, so we're constantly living with the anxiety of trying to keep our standards up. The goal always seems to be just beyond us because we're always trying for the perfect statement."

Despite the hazards, Ailey's uniquely multiracial American Dance Theatre has left an indelible mark on the history of American dance. In more than 20 years, it has served as a creative force, as a spur to the careers of such distinguished dance artists as Judith Jamison, Dudley Williams, Mari Kajiwara and many others, and as a focus of educational activity.

And its popularity within its own dance orbit is unrivaled. The Ailey troupe is the only modern dance company in the country that has been able consistenly to attract sufficient audiences to play the Kennedy Center on its Washington visits, for instance.

Those visits have persisted annually since the Center opened in 1971. But the company's week of performances there which began last night promises to be one of the most exciting ever, by virtue of the new and diverse repertory.

Ailey's passion for the varieties of American dance experience has given his troupe its characteristic stamp. In two decades, the company has traversed a massive repertory of dances, ranging from the works of such pioneers as Pearl Primus, Katherine Dunham, Ted Shawn and Lester Horton to such relative tyros as Louis Falco, Rudy Perez, George Faison, Jennifer Muller and Kathryn Posin.

The growth of the repertoire has led inevitably to a much larger troupe than the seven dancers Ailey started with in 1958, and a far larger enterprise altogether. "It's become much more enormous than I ever would have dreamed of back in the '50s," he says. "I never even thought I'd have a company of my own, much less something of this dimension.

"Originally, I just wanted to say something about the black experience in my own choreography -- I started out to create a trilogy of works along these lines, and two of them, 'Blues Suite' and 'Revelations,' we've been doing ever since."

Ailey's activities have also expanded much beyond the company itself. A school that serves over 3,000 students in New York, and two junior companies which perform in schools, hospitals and community centers make up a large part of the Ailey endeavor these days. The 16-member Repertory Ensemble, and the Ailey workshop, numbering about 20 dancers, both participate along with the senior troupe in performances of Ailey's new "Memoria" during the current engagement.

All this costs money and depsite its popular success the Ailey company has peered over the brink of fiscal disaster more than once. Nowadays, with help from the National Endowment for the Arts and a reorganized company administration, things are somewhat steadier, Ailey says.

"We still have an enormous deficit every year," he says. "But at least we now have an excellent board of directors -- 30 people who really give of their time and energy, whos long-range planning keeps us from the hand-to-mouth existence that used to be our lot only five or six years ago.

"Funding is still a problem, of course, but I guess I'm calmer about it. We don't yet get the kind of help from the Arts Endowment some of the big ballet outfits do -- travel allowances and support for musicians, for instance -- but I think that anything that's not ballet isn't as much in favor with the powers that be."

Another goal that yet eludes Ailey is making his troupe accessible to people of all economic stations. "I've always wanted a company that would appeal not just to dance enthusiasts but to the general public, without condescension. But I think this means you have to go to the people, you can't expect them to come to you."

"Yet here we are playing the Kennedy Center Opera House -- I think lower-class blacks, for instance, can't help but feel out of place in these kinds of surroundings. And it's embarrassing to be selling tickets with a $14.50 top -- who the hell can afford it?"

Among the highlights of this week's performances will be two world premieres -- Kathryn Posin's "Later That Day," with music from the Philip Glass score, "Einstein on the Beach;" a new solo by company member Ulysses Dove for superstar Judith Jamison, who has returned to the company after a leave of absence. In addition, there'll be four Washington premieres, including Ailey's own "Memoria," a tribute to the late Joyce Trisler, longtime Ailey friend and associate, set to music by Keith Jarrett.

Continual expansion of the company repertoire has been one of Ailey's guiding principles from the start. He's particularly concerned about persihable classics of the past, especially those by black choreographers which might easily pass into oblivion but for the efforts of the American Dance Theater.

"Take a work like Talley Beatty's 'The Road of the Phoebe Snow' or his 'Congo Tango Palace,'" Ailey says. "I have wanted to keep fine works like these alive, which sometimes means programming them once or twice a week on an overloaded tour just to keep them going in the repertory.

"But it's important -- Beatty created his own special way of moving in these dances, and a whole picture of a black social milieu. It's imperative for the dancers to know this way of moving."

A similar case is Donald McKayle's "District Storyville" of 1962, a dance portrait of the New Orleans' red-light district, set to music by legendary jazzmen Sidney Bechet, Duke Ellington and Jelly Roll Morton. The work will reveive its first Washington performance Thursday evening (with repeats Saturday and Sunday evenings).

Aside from the works already mentioned, Washington will also be seeing the first Ailey company performances of Lar Lubovitch's "Les Noces," to the celebrated Stravinsky score, and George Faison's "Tilt," during the current engagement. Also on the week's program are Faison's "Suite Otis," John Butler's "Facets," and by Ailey himself, "The Mooche," "Masekela Langage," and "Revelations."

The tenacity of Ailey's commitment to dance makes it almost hard to believe his reply just a year ago when asked whether he'd do anything differently if he had it to do over.

"Would I do it," he exclaimed, a great barking roll of laughter shaking his husky frame. "Would I do it at all, that's really the question."