Flashback: 1981. A gifted screenwriter named Barry Levinson gets a shot at directing his own script, a personal film about Baltimore guys on the cusp of the '60s - and adulthood.

Released in 1982, "Diner" introduces four unknowns who define a new generation of actors. Steve Guttenberg is the jittery bridegroom, Mickey Rourke a seductive playboy, Daniel Stern a neglectful husband and Kevin Bacon, uh . . . Bacon is Fenwick, an alienated alcoholic, and the only one of the quartet who notices that when the guys get together they are articulate and funny, but when a woman comes near, they behave like jerks.Flash forward: 1991. Of this quartet, Bacon, whose romantic comedy "He Said, She Said" opened Feb. 22, and whose ensemble film "Queens Logic" - a working-class "Big Chill" - is due this month, has proved to be the most durable and versatile actor.

While Guttenberg jittered through lowbrow comedies and soda ads, while Rourke bared his rump in numerous film sex marathons, and while Stern narrated "The Wonder Years," Bacon portrayed an offbeat collection of marginal and mainstream types.

Kevin Bacon was born with the kind of bony face that can look either prehistoric or patrician. Even without his acting skill, which is considerable, his face gives him an enormous physical advantage. Which other actor could conceivably play a high-school gymnast ("Footloose"), a working-stiff Everyman ("She's Having a Baby"), a rich-kid psycho-killer ("Criminal Law"), a dim-witted handyman ("Tremors"), and an intense medical student ("Flatliners")? Like the young Richard Widmark, Bacon can play it sinister or sexy. Or both.

"Maybe it's because I've always had two warring images of being an actor, that I've had two images as an actor," muses the unusually boyish Bacon, born in Philadelphia 32 years ago.

Taking refuge in his publicist's midtown Manhattan office, Bacon recounts his demanding schedule. Two movies in release; another, "Pyrates," due this summer; a recent guest-host gig on "Saturday Night Live;" a toddler son at home. Enough action to wind a marathon runner.

With his close-set eyes framed by owlish spectacles and his fine, translucent hair moussed into a Rod Stewart cockatoo shock, Bacon resembles a myopic rocker. As the actor plays air guitar on a miniature bat - a memento from Levinson's "The Natural" - he reveals both his boyish fantasies of stardom and his journeyman's seriousness about his craft.

"Part of my idea of what an actor was came from teen magazines," Bacon says, "which, when I was about 12, were moving away from the Beatles and toward young idols like Bobby Sherman, David Cassidy and Danny Bonaduce - you know, the teen-age heartthrobs. Part of me wanted that. The glamour. The girls."

"And then," he recalls with a toss of that cockatoo shock, "I started taking acting classes and met repertory actors and classical performers who weren't famous, but they made a living. They smoked cigarettes, drank coffee and breathed Shakespeare and Moliere. Part of me wanted to be those guys. And that was the part that got reinforced when I left Philadelphia for New York when I was 18."

Once in New York, there were theater workshops, the occasional Off-Broadway play, small roles in "Animal House" and "Friday the 13th," a stint playing an alcoholic teen on the soap opera "The Guiding Light," losing the part in "Ordinary People" to Timothy Hutton, and then, Bacon's breakthrough film.

"But I had no idea that "Diner" would amount to anything," he confesses, recalling his "limbo" period after making "Diner." For about six months after it was completed, the movie was shelved. Along with it, Bacon's film career.

He was back to waiting tables at the Allstate Cafe on New York's Upper West Side. While Bacon was bowling a few frames on his night off, a journalist who had just seen a press screening of "Diner" recognized him, complimented Bacon on his performance and told him the movie was slated for release. He looked at her in disbelief and admitted his low opinion of the film.

"In retrospect," he says today, "I love the movie. But at that point, I felt that `Diner' was financed and put together because it was about '60s guys with crazy cars and costumes like `Animal House' and `Porky's.' "

Bacon remembers, "At the time, I hated that I was very mumbly. Of course, what everyone loved was its naturalism.

"At the time, I hated that I couldn't tell the difference between the characters. Everyone loved - and raved - about the ensemble acting.

"At the time, I hated that it was dark and moody. Everyone loved the fact that it wasn't conventionally upbeat."

Reflecting on his past, Bacon says, it is always the seemingly insignificant event - like making "Diner" - that has proved to be significant.

Who, for instance, could guess that growing up in Philadelphia (he is the youngest of City Planner Edmund Bacon and wife Ruth's six children) and taking part in plays at the First Unitarian Church would lead to a career?

"I think I grew up in a family where creative expression was looked upon as the highest achievement," explains the actor who admits that "being the youngest in the brood, I definitely had a built-in audience." But even before he joined organized theatricals at church, Bacon says, "I liked to make noise in order to get attention. One of my earliest memories is a fantasy about being on stage, being admired and looked at."

Bacon was raised in a Locust Street townhouse near Rittenhouse Square. He played ball on the side streets, fondly remembers the Cherry Cokes and burgers in the drugstore at 21st and Chestnut, and went to public schools including Masterman.

He didn't attend college after graduating from high school in 1976, Bacon says, "because I knew what I wanted to study - acting." So he moved to New York, briefly bunking in his sister Karin's apartment.

The next apparently insignificant decision he made was the one that brought Bacon into closer contact with the repertory actors he so admires. "I was in New York, I had little or no money. It was after `Animal House' (1978), and I got an offer to do a television series called `Delta House' that was inspired by the film. They offered me more money than I ever dreamed of. But it meant relocating to L.A.," he says.

"At the same time, I was offered four lines in an Off-Broadway workshop - the Phoenix Theater - and I decided to stay in New York and build a career instead of grabbing the celebrity. Shortly after, I got a part in Marsha Norman's play `Getting Out.' "

Another "defining moment" in Bacon's apprenticeship came when he was on "The Guiding Light," in about 1981. "There was a certain financial security for me," he says. "And a certain artistic security, because working on daytime television enabled me sometimes to do plays at night. Then `Guiding Light' offered to renew. I had no other job, not even any job prospects. I thought, `I'm not getting any better as an actor, I'm getting worse.' I didn't renew. Two weeks later I got cast in `Diner.' "

For an actor frequently cast as a roaming Romeo - the comic premise of "He Said, She Said" is that his character can't commit to his girlfriend; the comic premise of "Queens Logic" is that his character repels the women he'd like to be with - Bacon has had a remarkably stable personal life. For several years he was involved with Tracy Pollan, who subsequently married Michael J. Fox. He then met and married actress Kyra Sedgwick (who plays the rebellious daughter in "Mr. & Mrs. Bridge" and who co-stars with Bacon in the forthcoming "Pyrates"). Their child, Travis, is now 18 months old.

Do they contemplate more children? "Since I've found my soul mate, I've always imagined a house with a bunch of rug rats falling all over the place and breaking stuff," Bacon answers. "We have the perfect careers for a two-career couple to have, because we can always work it so while one of us is working on a film, the other one has child-care responsibilities."

Ask if there is any performer whose career he aspires to and Bacon shrugs. "You don't aspire to careers. They unfold," he says. He's quick to add, however, that he admires "Meryl Streep's versatility, Cary Grant's combination of being at once funny, goofy and incredibly sexy and suave, and Robert De Niro's quality of being dangerous and vulnerable."

Bacon's ambition is not just to be a good actor, but to be an exemplary person. "I aspire to be Paul Newman - his ability to keep growing as an actor and his ability to combine being a big star with being a decent person."

Like Newman, Bacon resides in New York and Connecticut, far from Hollywood. Has he kept his integrity as an actor by not moving to Los Angeles?

"I love the movie biz," he says, sounding every bit the Angeleno. "I love the process. But I find that when I'm in L.A., my whole sense of self-worth is reflected in whether my pictures are hot or I'm hot. You're constantly reminded of that.

"New York is not a show-business town. Maybe it was when Broadway was in its heyday, but not now. But there's Wall Street, politics, ballet, the symphony - it's not just movies," Bacon reflects.

"I really feel when I'm here that I can keep some buffer between me and that part of the business that can eat away at you."