WHEN American Ballet Theatre launches its four-week series at the Kennedy Center Opera House this Wednesday, everyone's going to be wondering whether Mikhail Baryshnikov's recent installment as artistic director will have any visible effects.

The answer will rest with the performances, but a number of significant innovations are already apparent. A new "spread-the-action" policy is strikingly in evidence for the major roles: Baryshnikov and his advisors -- once again confounding the gossip merchants -- are divvying up the dancing assignments across the whole span of the company, to a degree unprecedented in recent ABT history.

Now that the particulars of casting have been announced for the first two weeks (much earlier than in past seasons, to the intense gratification of ticket purchasers), it's become clear that Baryshnikov is taking a new tack with the ABT dancers. No pricey, big-name "guest artists" will be present to commandeer major portions of the repertory. Nor will Baryshnikov himself he monopolizing any plums -- except for "Push Comes to Shove," which Twyla Tharp tailored to his idiosyncracies -- and every role in which he's appearing will also be danced by others in the troupe.

The casting seems to place greater trust in the abilities of the ABT personnel at all ranks than at any time in the past. Aside from the principals, each of whom will have new things to do, no fewer than 23 dancers will be tackling substantial new assignments in the first two weeks of the run alone. This should be not only a considerable boost to company morale, but also a bonanza for audiences -- every program will contain numbers of potentially exciting debuts.

For racial initiatives, such as the commissioning of new ballets and scores or the complete overhaul of shopworn classics, we will need to wait for future seasons.This season, we're getting one world premiere -- Baryshnikov's own mounting of the divertissements from the Petipa classic, "Raymonda" -- along with two ABT premieres: Frederick Ashton's "Les Rendezvous" and George Balanchine's "Prodigal Son." These are the first ballets by these masters the company has acquired in over three decades. We'll also be seeing Natalia Makarova's staging of the full-length "La Bayadere" for the first time in Washington. And through the "Giselle" production will be basically the David Blair version familiar here since its premiere at Carter Barron in 1968, it will have been subjected to what Baryshnikov calls a "healing process" with regard to stylistic details. There's also a hitherto unannounced bonus -- the duet called "Pas d'Esclave" on opening night, to be danced by Gelsey Kirkland and Patrick Bissell, will be a first foretaste of Baryshnikov's staging of divertissements from "Le Corsaire," in this case a pas de deux from Act I not previously mounted outside Russia.

The ballets that are new to the ABT repertory will be mostly new to the dances as well, and given this season's numerous alternate castings, that signifies a plethora of new interpretive possibilities. But the company staples will be heavily rotated as well -- "Les Sylphides," for example, will have three performances the first week, with three entirely different casts, marking role debuts for Cheryl Yeager, Victor Barbee, Chrisa Keramidas and Lisa Rinehart. The principals for the first of two performances of "Theme and Variations," as another instance, will be Cynthia Harvey and new ABT dancer Ronald Perry (formerly of the Dance Theatre of Harlem), and the roles will be "firsts" for both of them.

Baryshnikov hasn't entirely exempted himself from novelty either; on Thursday evening, he'll dance the male role in "Les Sylphides" for the first time since his arrival in the Western orbit. Kirkland will make her debut in Robbins' "Interplay," as well as in "Pas d'Esclave" and "Les Rendezvous." For Magali Messac, the company's one new principal, everything will be new except "Giselle." More of a surprise are the assignments at other company levels. Ruth Mayer, for instance -- longtime ABT soloist -- will portray the cowgirl lead in "Rodeo" for the first time. aJohan Renvall, just promoted to soloist rank, will be doing his first "Interplay." And many corps de ballet dancers share in the gravy. Pamela Nearhoof will dance in "Push Comes to Shove," for example; Robert La Fosse will have major new roles in "Prodigal Son," "Rodeo," "Interplay" and "Les Rendezvous."

In short, though the players are mostly the same, the bases they're covering are not, and it's going to be a whole new ball game.

A final bulletin on company developments new since last report: Principals Natalia Makarova and Anthony Dowell have both signed with ABT again for the year, though neither will appear in Washington; soloist George de la Pena is also returning to the company, and will dance here; and former musical director John Lanchbery has left -- the conductors for the season will be Alan Barker, Stewart Kershaw and Paul Connelly.