THERE'S THIS tubby kid in Barry Levinson's "Avalon" who doesn't get why people say "great aunt." Why, he wonders, can't it be "good aunt" or "fantastic aunt?" It also turns out he thinks it's "great ant."

He's just one of many Krichinskys, an extended family of Russian immigrants that have settled in Baltimore, and this is just one of many amusing occurrences in the movie. Those moments come without warning, in passing, mere asides in Levinson's 50-year family saga and, thankfully, they're all over the place. Ostensibly just comic relief, they are the movie's greatest strength; they ultimately save "Avalon" from its overly grandiose designs.

The last of a loosely autobiographical trilogy that includes "Diner" and "Tin Men," Levinson's latest has "pet project" written all over it. You can feel the earnest weight of preciousness in every scene. You can tell this sepia-toned, ensemble production (which includes Armin Mueller-Stahl, Joan Plowright, Elizabeth Perkins and Aidan Quinn) means more to Levinson than his commercially successful, hired-hand work in "Good Morning, Vietnam" and "Rain Man."

Beginning with the New World arrival of Krichinsky brother Mueller-Stahl (who lands -- all too conveniently -- amid a dazzling fireworks display on the Fourth of July), "Avalon" takes epic passage through other Independence Days, through turkey slicings, business openings, moves to the suburbs, family meetings, brotherly bickerings, birthdays and funerals. It also follows little grandson Michael (Elijah Wood), a likable kid who (not unlike a certain young Levinson) discovers that combination of mystery, frustration and banality referred to as growing up.

The vignettes are not uniformly effective. Some are tremendous: When the family gets its first TV, for instance, they turn it on and stare at it with hypnotic, breath-held stupefaction, unaware they're watching the test pattern. But other segments -- a red-herring of a flashback in which Mueller-Stahl recalls his aborted attempt to start a nightclub -- seem self-conscious, little more than epic padding.

Where "Avalon" works, as with "Diner" and "Tin Men," is where it's improvisory, comic and most artistically humble. In a multi-dialogue scene, the family elders (there are five Krichinsky brothers in all) sit around wondering what the world has come to, where people get mugged. Money, they conclude, with philosophical simplicity. There is also a piece of comedic heaven, a Levinson take on the Abbott and Costello "Who's on first?" routine: Mueller-Stahl is trying to recall the name of a western in which a stagecoach is involved. "Stagecoach," a brother tells him. But Mueller-Stahl doesn't get it and re-explains the plot: It has John Wayne in it and it's about a stagecoach. His brother tries again: "Stagecoach."

"That's what I'm saying," says Mueller-Stahl . . .

AVALON (PG) -- K-B Cinema.