The scenes in "Diner," which opens today at the Dupont Circle, almost always recall believable, intriguing fragments of experience. They're also attractively performed by a young cast full of sincerity and humorous individuality. But authenticity isn't everything and "Diner" ends up an oddly disappointing nice try.

Writer Barry Levinson makes his directing debut on a presumably autobiographical screenplay intended to recall the quality of friendship shared by five or six young men in Baltimore at the end of the 1950s. The episodes unfold over several days during the Christmas holiday of 1959. The characters are anticipating one of the biggest sporting events in the history of their hometown--the National Football League championship game between the Colts and Giants--as well as a momentous social event within their own circle--the marriage of Eddie (Steve Guttenberg), a thickheaded but brashly likable kid whose enthusiasm for football has prompted him to suggest that the wedding may be canceled if his fiance' fails a monster trivia exam he's assembled with outrageous self-righteousness.

In fact, a passion for trivia expertise is shared by a number of the guys. "Shrevie" (Daniel Stern), a vaguely discontented young married man who works in a TV appliance store, is a pedantic compendium of facts and figures on the subject of popular music. Fenwick (Kevin Bacon), a sullen flake from a well-to-do family, has evidently dropped out of college but gets his kicks beating the undergrads on "College Bowl" to the answers. The other two principal figures--Mickey Rourke as "Boogie," a small-scale manipulator whose sweet and oddly gallant disposition tends to excuse his inept scheming, and Timothy Daly as Billy, a pensive grad student--are free of arcane specialties, but they're struggling with romantic entanglements.

Evidently in their early twenties, the pals are former high school classmates still clinging to an adolescent style of companionship, epitomized by all-night bull sessions at a favorite hangout, the Fells Point Diner, where the talk is fueled by exotic dishes like french fries with brown gravy. The unifying perception, I gather, is that they're edging inevitably toward adulthood but prefer to prolong their footloose youth as long as possible.

Although married, Shrevie remains emotionally dependent on the gang, and one rather suspects that he always will. Ditto for Eddie as he obliviously approaches matrimony. The other guys appear to possess broader emotional resources, but when we encounter them, they're messed up in ways that look potentially drastic. Fenwick seems to be on the edge of a violent flip-out. Boogie gets himself in trouble with a bookie and a hot date. Billy, perhaps foreshadowing the coming Age of Role Reversals, expresses a willingness to marry his pregnant girlfriend, but she's too preoccupied with a burgeoning TV executive career to feel keen on either motherhood or marriage.

Ultimately, Levinson writes off all these apparent crises, implying that nothing much was at stake after all. This fizzle does a peculiar disservice to the situations which were compelling, like the estrangement between Shrevie and his wife, Beth (beautifully played by Ellen Barkin, who knows how to express the emotions of a rather blowsy, ignorant, unloved girl without getting mawkish about it), which prompts her to fall back for consolation on Boogie, whose crude stunts in the pursuit of sex conceal a fundamental gallantry and gentleness with women. The most touching moment in the film occurs when Beth asks Boogie a painfully revealing question: "Did you care about me when we were going out? I don't mean just because you could do stuff to me . . ."

Boogie doesn't abuse her confidence or add to her misery, although Levinson teases us with another false lead that suggests he might.

I think Mickey Rourke, who was impressive last year as the solicitous arsonist who counseled William Hurt in "Body Heat," may ride the role of Boogie to considerable popularity. There's something infectiously likable and comforting about Rourke's personality. Perhaps it's this reassuring warmth that makes the feckless aspects of Boogie's behavior difficult to accept. Rourke makes more emotional sense as a guy who has grown out of adolescent dumbness and can be trusted implicitly. I don't believe deviousness is really his line.

The irony of "Diner" may be that Barry Levinson's failure to make dramatic sense of his nostalgic reflections will seem beside the point when people remember that this tentative movie provided Mickey Rourke with a decisive starring opportunity.