Watching this movie is a bit like stepping into a time warp–and it’s not just that the story is set in 1978. Rather it’s that the good-natured mood of “Roll Bounce” is reminiscent of the rowdy but unthreatening attitude of comedies of that period, both films like “Car Wash” and television shows like “Good Times.” And it’s got roller skates, too!

The picture stars Bow Wow, who’s left his rap and trademark braids behind to play Xavier (“X” for short) Smith, a South Side Chicago kid whose mom has recently died and who lives with his widowed father Curtis (Chi McBride) and baby sister. X is a good kid, but both he and his dad–who’s keeping the fact that he’s without a job and is searching desperately for another a secret, pretending to go off to work every morning–are having trouble coping with their loss. X and his neighborhood pals–who spend most of their time jokingly dissing one another–are bummed out that the local skating rink is closing down, and together with Tori (Jurnee Smollett), a girl who’s just moved in across the street, they all hop the train to the North Side to skate there. There they bump heads with the champion rink team led by the incredibly smooth, incredibly popular Sweetness (Wesley Jonathan), and X bumps into a girl named Naomi (Meagan Good) who knocks him for a loop. Over the course of a couple hours, all the sorts of things you’d expect happen. X and his dad quarrel but eventually bond. Curtis also connects with Tori’s single mom, with whom he’d initially sparred. X and Naomi get together after a hesitant start. Tori, meanwhile loses her braces, changes from ugly duckling to swan, and steals the heart of the loud-mouth member of the crew who’s been freest with insults in her direction. And, of course, X and his pals compete in a big contest against Sweetness and his arrogant buddies, and–win or lose–they’ll earn the respect of those who’d previously dismissed them as second-raters. None of this will be in the least surprising, and even more extraneous bits like the occasional interruptions by a couple of garbagemen (Mike Epps and Charlie Murphy) are as familiar as old vaudeville routines. But all of it has a certain innocent charm, and it’s directed (by Malcom D. Lee) and played by the ensemble cast with such affection that, like “Barbershop,” it can’t help but make you feel happy. Bow Wow, looking as though he might have stepped off the set of “Welcome Back, Kotter,” demonstrates some real acting chops, as well as considerable skating ability, as X, and McBride (best remembered as the principal in “Boston Public”) cuts a figure at once imposing and vulnerable as his father; the two also interact well with one another, skillfully preventing the more dramatic moments from sliding into bathos. The rest of the cast are a likable lot, with Good and Smollett striking all the right poses and the four young guys who make up X’s gang–Brandon T. Jackson, Rick Gonzalez, Khleo Thomas and Marcus T. Paulk–showing great rapport. Even the villains aren’t a terrible bunch, with Jonathan keeping Sweetness just this side of despicability. The production design (William Elliott) and costumes (Danielle Hollowell) capture the period nicely and the cinematography (J. Michael Muro) catches their colorful character without getting too garish, even in the over-the-top skating rink scenes. (The sole flaw is that the Chicago setting isn’t exploited as effectively as it might have been.) And there’s a fine collection of period pop tunes on the soundtrack to keep toes tapping.

“Roll Bounce” is cinematic cotton candy, but it goes down easy, even if there’s not a lot of nourishment in it. Even viewers who don’t remember the seventies should find the decade a nice era to visit in this company.