Rueful comedy from a sharp new playwright

A Weekend Near Madison. Play by Kathleen Tolan. Directed by Emily Mann. A new playwright of sharp perceptions, humor, and tender sensibilities has come to Off Broadway via the ever resourceful Actors Theater of Louisville. Kathleen Tolan's ''A Weekend Near Madison'' has opened in a first-rate production at the Astor Place Theatre.

The rueful comedy reunites four former college friends in the comfortably modern frame house occupied by David Rabinowitz (Bill Mesnik), a successful psychotherapist, and his novelist-wife, Doe (Robin Groves). In the way of such gatherings, the reunion is more disorienting than reassuring as the young adults face the consequences of choices made in the far-off days of the 1960s.

Miss Tolan treats their dilemmas with clear-eyed forthrightness, an approach that wins the spectator's sympathy for these less than clear-eyed adults. The crisis over the suicide of one of David's patients brings to a head the domestic conflict that has been threatening an apparently successful marriage.

The couple's deep love for each other resolves the conflict. Reunionist Jimmy (Randle Mell), a painter and art-gallery curator, confesses to ''missing the time when there was more hope.'' Jimmy comes to Wisconsin to discover that Vanessa (Mary McDonnell), a one-time love for whom he still cherishes affection, has opted for a lesbian life style. Nessa and her young companion, Samantha (Holly Hunter), are fellow musicians in a women's performing group.

The skill, sensitivity, and insight with which Miss Tolan examines these youngish Americans and their relationships results in a group portrait that is relevant, authentic, and touching. Even when she makes the spectator laugh at her characters' earnest self-analysis, '60s jargon, and uncertain efforts to find focus in their lives, the author leaves no doubt that the subjects of her humor are the objects of her affection.

Nessa is the most far-out of the quartet - a mixed-up feminist whose sense of morality is as casual as it is confused. To Jimmy's mounting outrage, Nessa proposes bearing his child in order that she and Samantha may adopt it. The idea of a father's rights and a normal parenting environment never occurs to Nessa.

Emily Mann has staged a performance ideally suited to the Tolan design and mood. The players catch the atmosphere and feelings of an occasion when (to paraphrase one of them) old friends meet and important things are said. If they have not necessarily found their ways, the four friends at least have found their way to the Wisconsin rendezvous where discoveries are made.

The production is smartly served by designers Thomas Lynch (scenery), Karen Gerson (costumes), Craig Miller (lighting), and Tom Gould, whose sound effects range from early-autumn thunder to the recurrent barking of the Rabinowitzes' ever-present offstage dog.