By JANET MASLIN

NEW YORK -- Prosperous Philippe (Wladimir Yordanoff) arrives at his family's modest little restaurant fresh from a television appearance about which he has been nervous. So he fishes for compliments in the shark-infested waters of a family gathering. "It's a stupid detail, but you stuttered at one point," points out Betty (Agnes Jaoui), his rebellious and outspoken sister. Then Philippe's domineering mother (Claire Maurier) and dim, dainty wife (Catherine Frot) voice their unhelpful opinions about Philippe's necktie. This is the not-so-welcoming atmosphere in which the astute French hit "Un Air de Famille" unfolds.

In the wishfully jolly atmosphere of a birthday party, the film brings together an awkward group of relatives and lets the squabbles begin. Set in nearly real time on a single evening and shot in enveloping Cinemascope despite its talky style, the film begins on a humorous note and goes on to find some universal truths in its family tensions. Of course, this group encounter winds up leveling everyone in sight.

As directed by the talented Cedric Klapisch, whose "When the Cat's Away" revealed a similar gift for wry observation, "Un Air de Famille" (or "Family Resemblances") has an interesting history. It began as a play written by two of the actors here, Ms. Jaoui and Jean-Pierre Bacri. (He plays Henri, the glum brother who runs the restaurant and was never his mother's favorite child.)

The play had a substantial run with the same actors who are seen here, which is why they work so artfully as an ensemble and so evidently know their characters inside out. The film won acting Cesars for Ms. Frot and Jean-Pierre Darroussin (as the self-effacing waiter who gets caught up in the family fireworks), and for its screenplay.

Though he has filmed the one-set play without opening it into the world beyond the restaurant, Klapisch does an expert job of freeing it from visual claustrophobia. And the restaurant seems all the more spacious since the truly cramped quarters are psychic pigeonholes that keep the characters trapped. It is gradually revealed that the family's proper bourgeois mother, who nags ceaselessly and invokes the French platitude "C'est normal" to justify her reasoning, has favored handsome Philippe and turned him into the least deserving of her children. Philippe curries favor in the business world, condescends to his siblings and routinely demeans his sweet wife, Yolande, whose birthday is being celebrated.

Betty's black leather jacket pretty well explains her attitude toward Philippe and their mother. The mother, for her part, is appalled by Betty's wardrobe, vocabulary and defiantly single status. Thanks to her, all three of the children have had painful difficulty in getting along with romantic partners. Betty deals brusquely with Denis, though he clearly cares for her; Henri scrambles to hide the fact that his wife has just left him.

These situations intersect in ways that are ruefully droll at first, then increasingly awkward as tensions rise. It's both funny and awful that a mother can ascribe her son's marital troubles to the fact that he was a late walker, for example. Klapisch carefully manipulates the film's tone, lighting and wide-screen intimacy to keep trouble simmering just below the surface, so that conventional dramatic fireworks would be beside the point. It's the indirect responses, like the joy and release that Yolande surprisingly experiences while dancing with Denis, or the sea change in Betty that swamps her mother, that tell the audience all it needs to know.