IF THE Negro Ensemble Company ever goes out of business, Frances Foster figures the jig is up.

"I just don't see myself working as I'm able to work at NEC in the commercial white theater," she says. "I'm too skinny and I'm too light. They just won't hire me. Nobody but Douglas Turner Ward would allow me to play a grandmother.... The big fat happy ladies, they're the only people who keep getting work."

On those occasions when her name is submitted for a major Broadway role, says Foster, "They'll tell my agent, 'Oh, Frances is a marvelous actress, but she's a little too cultured-looking' -- and that's a euphemism for she's not the mammy type."

It's true. She's not the mammy type. But as Everelda Philibert Griffin, the domineering, self-sacrificing older sisterin the NEC's "Nevis Mountain Dew" at Arena Stage's Kreeger Theater, Foster shows she can hold a stage as solidly as the least-cultured mammy that ever breathed.

Her complaint about the world of theater out there beyond the NEC's window is not simply that it won't employ her, says Foster, but that it refuses to produce black plays "where people are people and not the old caricatures -- the mammies and the 'kill the honkies' and the pimps...." (Mammies, it gradually becomes clear, are one of Foster's occupational obsessions.) In NEC productions, she says, "I see people who I recognize who are just trying to get by."

The boss of the NEC, Douglas Turner Ward, rejects the idea that he is engaged in a deliberate hunt for "affirmative" plays. "I'm not remotely interested in plays as identity-making," says Ward, whose own leading performance in "The River Niger" struck some as an act of reparation for all the weak, shiftless black fathers portrayed in theater, film, television and legend.

"The theater is not just to stroke you," he says. "What audiences need is some shred of truth. The one thing that I seek is dimensional art that tries to deal with human beings in their density and complexity."

But on the other hand, as he proceeds to explain, black playwrights may enjoy "a slight natural advantage in writing affirmatively."

"If you took a close in-depth study of the creative output in the writing field, you'd find that the white artists -- even from the blue collar -- they almost have to be frustrated... have to find themselves in alienation against the society," says Ward. Black playwrights "share the deep-seated aspirations of the characters they're writing about... because all black people are still struggling to overcome. A black person can grow up to be the president of the United States... but if a cabdriver is passing me by, I don't have a chance to hail him down and say, 'Lookie here, here's my pedigree.'"

If Ward were president, one of his first acts might be to sneak about $1.5 million out of some unwatched budget or other and allocate it to himself to buy and remodel the building at 133 Second Avenue in New York, where the NEC has its heqdquarters. The building contains a large theater on its first floor, but that, naturally, is not where the NEC conducts business. Its 145-seat home, reached by climbing two steep flights of stairs and ignoring a variety of challenges to the liberality of the New York City fire code, is a crude, uncomfortable, misshapen auditorium whose small size, according to Ward, means that even if a play sells out, "you're sentenced to a losing proposition."

The NEC and its landlords have come to the mutual conclusion that they are unsuited to each other, according to Ward. The landlords are looking for another tenant, "and we're just looking all over the place."

When it was founded in 1967 with a grant from the Ford Foundation, the NEC was a full-time, 52-weeks-a-year operation. The years since have seen a gradual paring down of the company's staff, schedule and foundation support -- although, says Ward, "we've never mentally allowed ourselves to think that we were going to go out of business."

It is a point of pride with him that the NEC "has never missed a payroll for actors and production people." But "we've been in situations where financially the show had to get on in 2 1/2 weeks," he adds.Ward has invariably directed the plays himself on those occasions. "I could not in good conscience ask another director to come in and do that," he explains.

"Sometimes I have joked and said I wonder what would happen if I had three weeks of full rehearsal," he says, adding, "I've worked out creative methods of using time to the ultimate so my week or two weeks is possibly equivalent to somebody else's four weeks."

Despite the NEC's bumper-to-bumper history of crunches, it has now survived for 12 years, a period during which black theater in America has mounted from a small backwater into a torrent. The NEC can probably take as large a share of the credit for that growth as any institution -- even if the kind of theater it has helped spawn does not always sit well with Ward or his colleagues.

One of those who helped Ward found the NEC, actor Robert Hooks, later tried his hand at starting a black repertory company in Washington -- and failed (although the heir to his D.C. Black Rep, the Rep, Inc., continues to operate out of a small, nondescript building at 3710 Georgia Ave. NW).

"Robert and I have taked about it a lot," says Ward. "I think that what Robert was attempting maybe was a little premature -- a sustaining, professional black repertory company. We're located in the [theater] capital with access to the best actors." Washington, he points out, not only has a relatively tiny population of actors, but offers them precious few opportunities to supplement their income. To compensate, says Ward, a Washington employer has to offer actors a far fatter salary.

When D.C. Black Rep went under, the NEC promptly found a place for several of the pieces of human flotsam and jetsam set adrift. Charles Brown, who has a small part in "Nevis Mountain Dew," was one of the actors who went almost directly from Hooks' company to Ward's, and to him the essential difference was D.C. Black Rep's aim of basically paying its own way through the box office.

"We did carwashes and all kinds of things to stir up money and audiences for our theater," says Brown, but even so, he recalls, there were a lot of empty seats whenever they tried to keep a show open beyond a few weeks. Another difference was the prior training of the actors -- the NEC may have had to "finetune" some of its actors, says Brown, but D.C. Black Rep had to train them from scratch. "We were teaching people who had never encountered a stage manager before."

In NEC's early years, it and black theater were more or less synonymous. Now that the company no longer enjoys quite so exclusive a jurisdiction, one of Ward's worries is that more and more black talent may fall under white control. He is especially incensed over Joseph Papp's planned "Third World Theater Company" and Papp's mention of Ward's name -- without his consent, he says -- as a possible participant. "It's Joe Papp's company, it's not a third world company," says Ward. "Third world people won't be making the decisions."

As for Papp's black and hispanic Shakespeare productions, "you have got the most powerless people in our society doing plays about political power," says Ward. "I don't see any interpretive justification for what they're doing." Papp's response to criticisms of his actors' vocal skills also touched a raw nerve. "He sort of left the implication," says Ward, "that if you thought they were bad now you should have seen them five months ago." As Ward sees it, any pronunciation and projection problems were a "reflection on the actors he had chosen, not the inherent weakness of all black actors.

"A third world concept does not threaten the NEC artistically," he says. But "if this is going to seriously affect the financing available to the autonomous black theater companies, then I think I'll have to have programmatic objections to it.... I'm concerned about the institution's ability to survive in the face of a juggernaut like Joe."

Nevertheless, he had lunch with the juggernaut recently and "Joe feels that his third world project is not intended to do what I'm talking about," says Ward dryly.

In person, wearing the all-purpose blue suit he reluctantly bought at his wife's urging and plucked from the closet last week for his trip to Washington, Ward is a bit of a juggernaut himself.The talkshow host with Ward for a guest doesn't have to bother compiling a long list of questions. One question will do. Just about any question and your time slot -- a half hour, an hour, whatever -- is filled.

"After you've talked to Doug, you'll squeeze us down to about five lines," NEC trouper Arthur French told an interviewer last week.

"After you've talked to Doug," chimed in Frances Foster, "you'll forget you ever talked to us." CAPTION: Picture 1, Douglas Turner Ward; Picture 2, Francis Foster, right, in "Nevis Mountain Dew": "not the mammy type."; Picture 3, Douglas Turner Ward acting in the Negro Ensemble Company's production of "Ceremonies in Dark Old Men."