"I know people are very angry," says playwright Constance Congdon. "And you know, it's a very bad thing to be angry in WASPdom. Anger is bad. You're not supposed to be angry."

But anger is what it's all about. At least, that's how Congdon sees it.

She's sitting in the front row of the empty, dark, over-air-conditioned Woolly Mammoth Theatre, drinking what must be very cold coffee from a plastic foam cup. She's in Washington doing research for her next play, "Hallie!," about Hallie Flanagan, founder and director of the Federal Theater Project, a Depression-era, government-sponsored regional theater company. She is also here to see the Woolly Mammoth's production of her play, "Tales of the Lost Formicans," which has been extended through Sept. 2.

Watching Congdon, you see where Cathy, the lead character in "Lost Formicans," comes from. Talking in short bursts. Stopping midway in a sentence, as if holding back something that might hurt someone's feelings. And then other times rambling, as if releasing this pent-up stream of consciousness.

Cathy and Congdon are, on the surface, liberated women. Products of the almighty Sexual Revolution. What's frustrating for them is seeing their female friends' lives still dictated by the actions of men. And they are frustrated to see older women still catering to men.

But when they dig deep, they realize they too are still directly affected by, and answer to, men.

Cathy is a feisty woman in her thirties whose husband leaves her for his pregnant 18-year-old girlfriend. Cathy, with her rebellious teenage son in tow, decides to leave New York for a suburb in Colorado, only to see her burly father slowly die from Alzheimer's disease; her son run away; her childhood girlfriend Judy, a divorcee with three kids, caught in the pathetic cycle of searching for Mr. Right; and her mother running around confused, shouting, "Where is God? Where is God?"

And Congdon's explanation for this wanton destruction of Cathy's idealistic existence?

Aliens. They control us through little slits in the atmosphere.

"Cathy turns out to be very much like a part of me," says Congdon. "She's that part of me that always wants to make everything all right. Make sure everyone has a good time. The 'Mary Tyler Moore' part of my personality. It's kind of a hard thing to admit, but it's true. 'Mary Tyler Moore' was written by a man. It was based on reality; just, there was a component missing: anger. A normal part of the personality. Yes, there is a lot of anger in this play. I'm still angry about a lot of things.

"It's hard to be a woman and not be angry," says Congdon.

Congdon, 45, divorced, raising one rebellious teenage son and living in Longmeadow, Mass. -- albeit originally from a suburb in Colorado -- first started writing plays in 1975 while teaching remedial reading at St. Mary's College in southern Maryland. She had published some of her poetry, but decided it wasn't enough. "I'm more of an extrovert," she says.

For her first production, in 1976 at St. Mary's, she chose to adapt the epic story of Gilgamesh, an ancient warrior. "I wasn't interested in writing a play that stays in one place," Congdon explains. "I wanted to do an incredible production."

She wrote the whole play in longhand. "I'd put my son on the school bus at 9, then sit down for three hours and write, like Margaret Mitchell," she says. She hired professional costumers. She had elaborate sets. "And it was my launching."

Shortly thereafter, Congdon moved to New England with her husband, a college librarian. She worked at Springfield College, where she met the women on whom she eventually based her composite character, Judy.

"They were living on second salaries, but they were the heads of households, and they were divorced, so they were living in a bare-minimum way," says Congdon. "They would have all the kids, but the husband would have the new car -- because his employment wasn't even touched.

"And because he didn't have the kids," she continues, "his love life was great. These women had no love life. No one was interested in going out with them because they had kids. And they weren't meeting the kind of men they wanted to. They are completely invisible, these women. Completely forgotten."

Congdon went on to earn her master's of fine arts at the University of Massachusetts and move into writing full time. One of her productions, "No Mercy," was a co-winner of Actors Theatre of Louisville's 1985 Great Play Contest. Several have been staged in Europe. "Tales of the Lost Formicans" was the darling of the Humana Festival at the Louisville theater last year.

Congdon also writes approximately one children's play a year -- mostly adaptations -- in conjunction with the Children's Theatre Company of Minneapolis. One of her plays for them, an adaptation of Mark Strand and Red Grooms's "Rembrandt Takes a Walk," was performed recently in Moscow.

Until this spring, however, none of Congdon's plays had been produced in New York. "Formicans" was the first. She prefers working with regional theaters. For a while, Congdon was the resident playwright at the Hartford Stage Company in Connecticut, where she did a string of adaptations: Mark Twain and Charles Dudley Warner's "The Gilded Age," and an opera libretto of Charlotte Perkins Gilman's novella "The Yellow Wallpaper."

"It was exciting," she says now, "but working on other people's plays kept me from writing my own."

So, three years ago, she did.

"I wanted to do two things: I wanted to write a play completely for myself and my friends," she says. "I had just come off this adaptation project and I was just feeling kind of boxed in.

"I also had felt the need to tell the story of my father's illness because there were all these stories on Alzheimer's today. There were some TV movies. I guess the one that Joanne Woodward did was really good, because her mother really had Alzheimer's. But whenever something like that is exploited for its central pathetic nature, it bothers me, because it seems to be a worship of victimization really. ... I think the intent is to exploit something that is incredibly sad and you watch it and, you know, it doesn't give anyone any more perspective. I was sort of angry about how that subject matter had been dealt with."

She started writing about her father's illness and her wacky, bitter girlfriends and she found that she had a lot of individual scenes, but nothing to really string it all together. And no way to start it.

Then one day, the muffler on her car broke.

"I went to the mall to get it fixed," she says, "and I got stuck at the Firehouse Pizza, which is this franchise pizza place, and it was completely deserted. And I thought, 'I am going to sit here, and just going to relax. And by the time my muffler is done I will have something.' "

That something was the opening monologue.

"Chair. Sit Upon. That which is used for sitting or eating or some other ritual," she recites. "I just enjoyed it so much when I finished writing it. And I kept thinking, 'What in the hell is this? You know, it's so strange. Who in the world could be saying this?' And that's where the idea for the aliens came from. It really came out of my subconscious.

"I look back now and go, 'Well, I know exactly what I was doing. I was objectifying things that were very painful in an effort to get perspective.' It allowed me to write about it. So, I had to back up way, way, way back up here," she says, reaching as far back as she can, "to look at it not only because it was painful to get close, but also to find out what is essential."

She decided to use the aliens as anthropologists, who come back "15 Earths" in time, to try to figure out what these people are doing -- and why. They are gentle creatures, the aliens, who study found objects such as a Formica table and chrome kitchen chairs -- the central meeting place for Cathy's family. Relics from American middle-class suburbia.

"I had this growing frustration of being apologetic for being from suburbia," she says. "I thought, 'Too many great people come from suburbia. How bad can it be?'

"Then I started thinking, 'What is it??? What is this culture, this American suburban culture that is sort of giving birth to all sorts of people? Not everybody interesting comes from an urban environment. What's there?' It already made me laugh thinking about it.

"So, I have this description of the chair and I looked at it and said, 'Well, it sounds like an anthropologist to me.' And what I discovered by the time I finished the play was that, in fact, they aren't really from another planet. They are just us, from the future, looking back."

But listen, she wants to set the record straight. The play, filled with so much anger and bitterness and frustration, may be somewhat autobiographical -- but not completely. Congdon's ex-husband didn't leave her for a pretty, pregnant coed.

"No, no," she says, with a smile. "He's a very nice man."