Peter Sellars will announce today his long-anticipated plans for the formation of the American National Theater at the Kennedy Center, a company its 27-year-old director not only envisions as altering the face of theater at the Center, but also energizing other theater groups across the country.

The plans -- which embrace everything from significantly lower ticket prices to the kind of dramatic fare that Sellars believes can counter the commercial theater's growing propensity to "do television" -- constitute a sharp break from the Center's past. They represent the first steps in what he sees as a five-year program to build a "heavily subsidized" national theater company on a par with such prestigious institutions as the National Theatre of Great Britain or the Comedie Francaise.

"The theater is the most depressed art form in America," Sellars said yesterday. "Either we continue with quick fixes, or we recognize that we've got to rethink the whole thing from the bottom up. That's what we'll be doing over the next five years -- radically rethinking the way theater is done.

"I see it as five years of research and development. Kodak and Polaroid recognize the value of research and development and know that after five years they'll come up with a better camera. It should be the same for theater. In this charter season, we'll be floating balloons and testing a wide range of work. But we'll also be laying an extensive foundation for the future. We can sit here and do 'Masterpiece Theatre' or we can do something that will change the status of theater in America."

Sellars, a leading avant-garde director hired by the Center last July, said the American National Theater's first production, Shakespeare's history play, "Henry IV, Part I," will open in the Eisenhower Theater on March 23 for a five-week run. To be directed by Timothy Mayer, it will star John Heard as Prince Hal, John McMartin as Henry IV and Patti Lupone as Lady Percy. Characterizing the play as "really, a show about Washington," Sellars said that "it is very important to raise the level of political discourse here, to have a poet, not an ad agency or a propagandist, tell us where we stand as a nation. I want to reclaim Shakespeare for Americans."

Tickets for "Henry IV, Part I," and all ensuing productions of the American National Theater will be priced at $15 and $20 -- a significant reduction from prevailing ticket scale, which went as high as $32.50 last year for the Dustin Hoffman revival of "Death of a Salesman." The Center's specially priced ticket policies will be maintained, making it possible for senior citizens, the handicapped, the military and students to attend a play at the Center for as little as $7.50.

For Sellars, lower ticket prices will not merely open up the Center to a more broadly based audience. They are also an expression of his belief that meaningful theater can no longer pay for itself in America and that it's foolish to pretend otherwise. Under the new price structure, he said, "even a standing room only, runaway hit in the Eisenhower Theater will lose money. That's very important. I don't want the Eisenhower to be treated as a commercial house. The American National Theater is a gift to the American people and it will be philanthropically supported. The public must understand that at no point does the ticket price pay for what it is seeing."

At this time, the source of funding for the American National Theater, aside from an initial $5 million already in the coffers, is vague, although the company will clearly require massive underwriting to survive. "We'll also be reinventing how theater is financed. Right now, we have no government subsidy, nor are we going to ask for it," Sellars said.

If the iconoclastic Sellars has his way, however -- and the Center's chairman Roger Stevens, has given him "carte blanche" -- theater in the marbled complex along the Potomac will never be the same again.

The Eisenhower, which has frequently housed Broadway tryouts and touring shows, will now be used for major productions of the American National Theater. After "Henry IV, Part I," Sellars himself will direct "The Count of Monte Cristo," the 19th-century melodrama that served as a star vehicle for actor James O'Neill, father of playwright Eugene O'Neill. The swashbuckler, which will open on May 11, was one of the most popular plays of its day. Sellars, who is particularly drawn to the neglected American dramatic repertory of the past century, described it "as a left-handed way of kicking off our policy of doing one play by Eugene O'Neill a year."

Although he has productions lined up for the Eisenhower through December, the only other title Sellars disclosed was "Come on Over" (alternately called "Embassy Row"), a never-produced comedy about Washington by Mae West, which his staff discovered in manuscript form at the Library of Congress. It will open June 29. "She's a very shrewd woman," said Sellars, "one of the great playwrights."

More experimental work is envisioned for the Theater Lab, a large, open room on the top floor of the Center, which has been infrequently used in recent seasons. Beginning in May, "it will be a place where genuine pioneering work can be done," said Sellars, who plans to rename it the Free Theater. No admission will be charged for productions playing there.

In yet another precedent-setting change, Sellars will devote the Terrace Theater, also on the top floor of the Center, to productions imported from or developed in collaboration with other theaters across the country. "You should be able to come to the Kennedy Center and ask, 'What's going on today in theater in America?' and then find out," he said. The work could come from a "well-funded flagship regional theater like the Tyrone Guthrie or from a little basement theater in Albuquerque, where two people act and paint the sets," he said. The Terrace programming will also get under way in May.

One of the immediate consequences of Sellars' policies is that the Center will largely cease to function as a touring house for Broadway plays, although Broadway musicals will continue to be presented in the Opera House. "I do not regard Washington as a tryout town," he said. "We're not producing anything for Broadway. We're producing for here." As a result, the city's most prosperous commercial theater, the National Theatre on E Street NW, will pretty much have the pick of Broadway's diminishing wares.

Instead, Sellars said he aims to make the Center both a crossroads and a catalyst for the American theater as a whole. To that end, he has appointed 15 members of what will ultimately be a 20-member board of artistic advisers, "whose work we admire and who will have their eyes and ears to the ground for us." They include director/actor Orson Welles; entertainer Harry Belafonte; the artistic director of the Tyrone Guthrie in Minneapolis, Liviu Ciulei; the founder of New York's LaMama Experimental Theater Club, Ellen Stewart; performance artists Robert Wilson, Laurie Anderson and Meredith Monk; and documentary filmmaker Frederick Wiseman. At least half of them are currently planning productions for the Center, Sellars said.

To encourage as much freedom as possible in theater-going, the Center will scrap its traditional subscription plans, which lock a patron in advance into a particular night of the week for a series of given shows. Instead, starting next month, the Center will sell memberships in the American National Theater for $75 and $100, which will entitle the purchaser to four and six passes, respectively. The passes will be good for any play and may be used in any fashion the purchaser chooses -- six passes for one play, for example, or one pass for each of six plays.

Until now, the Center's theater program has been shaped largely by one man, Roger Stevens, who confessed his sense of "relief" in turning the reins over to Sellars. "What I'm doing is saying to Peter, 'This is your baby. Live with it,' " Stevens said. "I wouldn't want to second-guess him any more than I'd want anyone trying to second-guess me. He's got a lot of pretty spectacular ideas and I don't want to get mixed up in any of them." Although Stevens does not rule out producing plays himself commercially in New York under the banner of Whitehead/Stevens, his private production company, he will no longer perform that function at the Center. "My first order of business at the Center is getting an endowment in order," he said.

In the past few years, Stevens has had to devote an increasing share of his energies to the Center's rocky finances. After extensive lobbying, he was able to persuade Congress last October to waive $33 million in compound interest on the bonds that financed the construction of the facility. Some close observers say the battle put him under enormous pressure and left him exhausted.

At about the same time, the Center also posted a deficit of $2 million for fiscal 1984, its first loss since opening in 1971. "Actually, I view that deficit as a significant advantage," Sellars commented yesterday. "It is proof that the theater is not working as it is."

Stevens now believes it is critical to proceed with the establishment of a private endowment to underwrite the Center's costly programs in dance, music, opera and theater. "What I would really like to see is $30 million in funding, raised over the next three years, of which $10 million would be working capital," he said.

Some of that money would presumably be earmarked for the American National Theater, which is currently financed jointly by the American National Theater and Academy (ANTA) and the Center itself, each of which contributes $1 million annually to the budget. ANTA was chartered by Congress in 1935 as the country's official national theater, but Congress never voted appropriations and, despite fitful attempts at programming over the years, its sole asset by the late 1970s was ANTA Theater in New York. The sale of that theater netted $5 million, which ANTA is turning over in five yearly installments to the American National Theater.

Sellars, who put his budget for the first season at $6 million, underscored the necessity for aggressive fund raising; with the lowered ticket prices, box-office revenues are expected to produce little more than one-third of that sum. "At first, at least $2 1/2 million will have to be raised annually," he said. "Part of our funding scheme involves the participation of recording and movie industries. Our complete budget is barely a line item in your average Hollywood movie. But we share the same actors and some of the same writers. Time is we shared the resources." Sellars said he has been talking to "major rock stars," but refused at this point to elaborate on specific projects.

He also intends to bring American novelists under the umbrella of the American National Theater, by commissioning five leading writers a year to turn out their first play, in collaboration with a stage director. "My attitude is let's give them a chance. It should yield us a substantial body of work," he said, adding that a strong contender for producton next season is his own dramatization of Theodore Dreiser's "Sister Carrie."

In a relatively brief span of time, Sellars has earned a national reputation for his unconventional productions of theater and opera at such institutions as the Boston Shakespeare Company, the Tyrone Guthrie Theater and the Chicago Lyric Opera. For some, he is "Peck's bad boy of the theater," but his supporters view him as an innovator, and in 1983 the MacArthur Foundation acknowledged his creativity with a five-year, no-strings-attached grant. Sellars' ambitious plans to transform the Center are certain to provoke strong reaction not only from what has been its generally conservative constituency, but also from the New York theater community, which regards New York as the logical home for any national theater.

"Five years from now, I'll be interested in whether anyone thinks we've succeeded or failed. Until then, I'll keep working," Sellars said.

Last week, he met with the Center trustees and laid out his vision for the future. "They had nothing but support," he said. "Many of them were present for earlier renaissances in the American theater and they were gratified to see the flickering again."

"I don't expect Peter to turn out hit after hit," said Stevens. "He'll make a lot of mistakes. Who hasn't in the theater?"