Between 8 p.m. March 11 and midnight April 2, more than 100 pieces of Soviet music, ballet, mime and spoken theater will have their American premieres in Boston, according to a schedule made public yesterday.

In a press conference at the Massachusetts State House, Sarah Caldwell, artistic director of the Opera Company of Boston, was joined by Soviet and Massachusetts officials to announce details of the massive "Making Music Together" festival that will escalate cultural exchange to a new level.

Events that were announced in September, when plans for "MMT" were first made public, remain the highlights of the three-week event. But yesterday's conference filled in details of the festival, which will bring 285 Soviet performing artists to Boston. And the program has expanded significantly.

Central figures in the festival remain Soviet composer Rodion Shchedrin and his wife Maya Plisetskaya, the prima ballerina of the Bolshoi. These two originated the idea of the festival in a series of meetings with Caldwell over the past 10 years, and much of the event seemed to be a showcase of their work. Major festival events announced earlier include the American premieres of Shchedrin's opera "Dead Souls," based on the satirical novel by Gogol, and three ballets based on classics of Russian literature with music by Shchedrin and choreography by Plisetskaya: "Anna Karenina," "The Sea Gull" and "The Lady With a Small Dog."

In the new announcement, Shchedrin was flanked by 12 Soviet composers who will be "profiled" in concerts during the festival and many others who will have one or two works played.

There will be four or five festival events on most days, at such locations as Symphony Hall, the Opera House, the Wang Center, the Wilbur Theater and the (Roman Catholic) Cathedral of the Holy Cross, as well as the campuses of the New England Conservatory, Boston University and Harvard. Frequently, two festival events will be scheduled simultaneously at different locations.

Next to Shchedrin in prominence (and more interesting to connoisseurs of modern music) will be Alfred Schnittke, a composer whose vivid imagination and willingness to experiment have often put him in trouble with the conservative Soviet musical establishment. The American premiere of Schnittke's "Requiem" was announced previously, but yesterday's conference added a lot more of his music to the schedule -- notably his Fourth Symphony (based on liturgical themes), which will be premiered with the "Requiem" March 19 in the Cathedral. Other works by Schnittke will be scattered throughout the festival, and he will be featured in a "Profile Concert" March 21.

Other composers receiving "Profile Concerts" will be Karen Khachaturian, Boris Chaikovsky, Boris Tishenko, Andrey Petrov, Giya Kancheli, Sofia Gubaldulina, Vitautas Laurushas, Tchari Nurimov, Georgi Dmitriev, and Tikhon Khrennikov. Many of these composers are virtually unknown in the United States. The festival may help to improve opinions of one composer on the list: Khrennikov. He has been the head of the Composers' Union since the Stalin era and has had a largely negative image here because of his prominent role in the troubles of Dmitri Shostakovich and the widespread resentment toward him of Soviet musicians who have defected to the West.

A "return engagement," in which Moscow and possibly Leningrad will be invaded by American composers and performers, is scheduled for next year.