"The company is dancing absolutely brilliantly right now," says Arthur Mitchell by phone from New York. "They've improved so much. Everything has just deepened -- the dancing has more body, more weight, more substance."

The company is the Dance Theatre of Harlem, which Mitchell founded 15 years ago with the late Karel Shook, and which has evolved from a showcase for black classical dancers into one of the globe's leading ballet troupes. DTH returns to Washington Tuesday night with a gala program launching a season at the Kennedy Center Opera House that will extend for two weeks for the first time ever.

John McFall's "Toccata e Due Canzoni" will have its world premiere Wednesday evening. "It doesn't tell a story," Mitchell says, "but it's powerfully dramatic and technically very difficult. And it's a kind of ballet the company has never tackled before -- it calls for an aggressive quality something like what you see in Anna Sokolow's choreography."

A company premiere will be Billy Wilson's "Concerto in F," to music by Gershwin, originally staged for Alvin Ailey's modern dance company. "Wilson has put it on toe shoes for us," Mitchell says. "It's basically what he did for Alvin, but we give it another look, our own style. And doing it on pointe is what Billy had in mind when he created it."

The company also will be dancing Jerome Robbins' "Fancy Free," George Balanchine's "Stars and Stripes" and Domy Reiter-Soffer's "La Mer," here for the first time. Among the other ballets scheduled is Valerie Bettis' "A Streetcar Named Desire," the DTH performance of which is the subject of a new "Dance in America" special on PBS that airs locally later this month. "The ballet lends itself even more to television than the stage," says Mitchell. "We also had special sets made for TV, and it ends up being more like watching a movie than a ballet."

DTH taped "Streetcar" in Denmark while the company was on a 10-week European tour last fall. On the same trip, a crew from "60 Minutes" followed Mitchell and the company around to film a profile scheduled for broadcast early this spring. The tour included stops in Denmark, Spain and France, including, for the first time, Paris. "We played there for a very successful two weeks," Mitchell notes. "It was the last of the major foreign cities we'd never visited, and for the dancers it was a kind of culmination, a crossing of a final hurdle in their acceptance of themselves as artists and of the company as a major troupe."

Another breakthrough -- of a surprising character -- will take place in this country next month for DTH. "I said to the board," Mitchell reports, "we've performed in London, Paris and the Metropolitan Opera, but we've never done a season in Harlem. So now, we're doing it, our first season in the community for which we're named, two weeks at the Aaron Davis Center starting March 25."