Greg Mottola is currently best known, to the extent that he’s known at all, as the director of “Superbad” — a movie that you’d think didn’t even have a director for as often as he was mentioned in the reviews. That film belonged more to its writers, Seth Rogen and Evan Goldberg, who based the main characters (played by Jonah Hill and Michael Cera) on themselves. Mottola’s direction was fine, but it wasn’t “his” movie.

“Adventureland” is. Mottola wrote it himself, and it feels like a more personal project. And that’s its chief strength, too. Though viewers might enter “Adventureland” expecting a raunchy teen comedy a la “Superbad,” what they’ll actually find is an earnest coming-of-age story that’s both funny and sweet.

It’s set in Pittsburgh in the summer of 1987, as a level-headed young man named James Brennan (Jesse Eisenberg) has just graduated from college with a very useful degree in comparative literature and Renaissance studies. His parents’ planned gift of a trip to Europe has fallen through due to money problems (1987 was a lot like 2009!), so James is forced to take a summer job before heading to grad school in the fall.

The best thing he can find is a gig working carnival games at the local amusement park, Adventureland, where his lifelong neighbor and ostensible best friend, Frigo (Matt Bush), has worked seemingly forever. (Frigo is one of those hyper-active friends whose main job is to annoy you. We’ve all had those.) The owners, husband-and-wife team Bobby (Bill Hader) and Paulette (Kristen Wiig), are easygoing if a bit dotty, and the other employees are generally kind. Apart from having to fleece customers (those games are impossible to win, you know) and occasionally hose down vomit, it’s not a bad job.

James instantly notices Em (Kristen Stewart), a headstrong girl his age who also works the games and has a strict policy of not taking any crap from anyone. (When a clueless co-worker refuses to date another employee because he’s Jewish, LOOK OUT.) Em and James are mutually attracted — him to her because of her worldly ways and experience, her to him because he’s adorkable and naive.

Lurking in the periphery are colorful characters like Joel (Martin Starr), a Jewish-born atheist who reads philosophy and despairs of ever getting a girl, and Mike (Ryan Reynolds) the maintenance man, who is married but still flirts (and then some) with the female Adventureland staff.

The story has the feel of one plucked from experience, and Mottola fills the movie with authentic little touches: sneaking your parents’ car out of the driveway late at night by putting it in neutral until you’re down the street; the young-adult gossip grapevine that turns every romantic encounter into a melodrama; an amusement park with baffling ride names like “Flighing Dutchman,” which wouldn’t make sense even if it were spelled correctly.

But more than that, it’s the characters’ honest relationships with each other that provide emotional heft to support the comedy. The plot doesn’t hinge on contrived misunderstandings or lies, and James and Em and the others react to each other the way real people react. I’d call the film a “romantic comedy” if that term didn’t have such a negative (formulaic, unrealistic) connotation.

The only characters who stick out uncomfortably are the park owners, played by “SNL” stalwarts Hader and Wiig, who are terribly funny but seem like they belong in a different movie. (Interesting point: Hader and Seth Rogen stood out the same way in “Superbad,” too, as the farcical cops.)

Eisenberg and Stewart, both amply experienced in Hollywood, nonetheless still have a youthful innocence about them that serves “Adventureland” well. Ryan Reynolds, usually a glib jokester, is believable as a cad (but a cad with emotions), and the under-appreciated Martin Starr lends credibility as the requisite gawky guy.

The film could have been set in 2009 rather than 1987 except for one crucial thing: a wistful comedy about young love ought to make the viewer feel nostalgic for a bygone time. Even viewers who are the same age as James and Em — and who therefore weren’t alive in 1987 — will appreciate the film’s yearning for the past, even if “the past” just means last summer.

B+ (1 hr., 47 min.; R, a lot of harsh profanity, a fair amount of vulgarity and sexual dialogue.)