Since its inception seven years ago, the Pro Femina Theatre has concentrated on plays developed during group improvisation. Now, for the first time, it has tackled a script by someone else, and its production of "Close Ties" shows a welcome move in the maturation of this small troupe.

"Close Ties" belongs to what might be labeled summer house plays. As in "On Golden Pond" and other works, the house serves as a place for a family to convene and thrash out problems, old and new. In this case the main question is what to do with Grandmother, an irascible old dear who is starting to forget things and behave strangely.

Grandmother loses no opportunity to mention her late husband, a paragon with whom no one, least of all her son-in-law, can compete, or to criticize her daughter, a frumpish and conventional housewife. "Great mothers produce boring children," she observes. She gets along better with her three adult granddaughters and teen-age grandson, who can regard her with affection without having to face the possibility of having her move in with them, a prospect her daughter is anticipating with mixed emotions.

The conflicts are predictable, as are the characters, and there are times when one wonders why this particular family has been immortalized on the stage. But by the end, once the subsidiary dramas have been dispensed with and the focus has narrowed to the unhappy question of whether to put Grandmother into a nursing home, the drama has become genuinely touching.

Each of the granddaughters is in a different stage of emotional upheaval, with the middle one, Evelyn, the most noticeably disturbed. Still suffering from her divorce from a sadistic but handsome creep, she has tried to freeze her feelings, refusing the attentions of a fellow graduate student she picked up in the library. She is the one drawn most intensely to her grandmother, although when it comes to figuring out a solution to the problem, it is not she who offers to make a sacrifice, but her 16-year-old brother, who wants to drop out of school and take care of the old woman.

Bess, the daughter, is convincingly torn between her strong feelings of duty toward her mother and her desire to be free of someone who is clearly dictatorial and demanding. The one character who never quite comes into focus is the son-in-law, Watson, a middle-class lawyer who seems unbecomingly anxious to put the old lady in a nursing home.

Playwright Elizabeth Diggs ends too many scenes by having one character or another stomp offstage in a temper, and her dialogue is occasionally marred by psychobabble. The technical aspects of the production are still at the workshop level, with a wooden altar decoration as a backdrop and an awkward arrangement for entrances and exits. Such amateurish touches as having the director, Dorothy Neumann, rise from her seat in the front row to help with a scene change don't help.

But the acting is generally strong. As the grandmother, Pamela Brown starts out being too rushed, but she relaxes as the play progresses. In the end we understand why at least some of her grandchildren are drawn to her, and share their sadness at her gradual decline. Cary Anne Spear is vivid and compelling as the disagreable, neurotic granddaughter Evelyn, and young Todd Hoffman is remarkably appealing as her teen-age brother. Neumann's direction is sensitive to the emotional subtleties of the drama, although it could be more so to the mechanical aspects.

"Close Ties," by Elizabeth Diggs, produced by the Pro Femina Theatre, directed by Dorothy Neumann, set by William Pucilowsky, lighting by Lea Hart, with Pamela Brown, Lawrence Lerer, Marie McKenzie, Laurel Lefkow, Carole Myers, Cary Anne Spear, Todd Hoffman, Christopher Hurt.

At the Grace Episcopal Church, Thursday through Sunday through June 26.