Abby Ryder Fortson (Margaret) with Rachel McAdams and Benny Safdie, who play her parents, in “Are You There God? It’s Me, Margaret.” (Dana Hawley, Lionsgate/TNS/The Minnesota Star Tribune)

There's no 60-year-old Margaret reminiscing about her adolescence in "Are You There God? It's Me, Margaret." But that sort of looking-back appeal is a big part of this terrific movie.

"Margaret" is based, of course, on the frank, 1970 Judy Blume book that became a mega-seller for young readers. Its endearing title character (likable, natural Abby Ryder Fortson) is at the in-between age when she's starting to think about getting her first period/bra/boyfriend.

All of that jams up against a family move from her beloved Manhattan to the less-beloved suburbs of New Jersey where, as if to add to her confusion, her parents have the nerve to be in a "mixed" marriage of a Jew (dad, played by director Benny Safdie) and a Christian (mom, played by Rachel McAdams). And Margaret misses her doting grandmother (Kathy Bates), whom she sees less often after the move. As they didn't yet say in the '70s, it's a lot.

The most notable thing about "Margaret," who turns to conversations with God for answers, is its kindness and gentleness, which also recalls Minneapolis writer Kate DiCamillo. Particularly striking is the incandescent McAdams, who gazes at her daughter with such joy that it lifts the movie, even when she's not onscreen.

Even the marginally mean characters — a classmate who welcomes Margaret but turns out to be a snot, estranged grandparents who are bigots — take stabs at being better. And their meanness ends up providing lessons the other characters need to learn.

I watched "Margaret" with a huge smile plastered on my face and a slight sinking feeling. What's the problem? Nothing blows up, which means this is not the kind of movie that is succeeding in theaters now.

Its commercial prospects also are complicated by the fact that, like Margaret, it falls into an in-between place: It's about a sixth-grader, and sixth-graders will probably enjoy it. But it feels more like it's aimed at the now-adults who loved "Margaret" when they were kids and look back fondly on the games they played and the 45s they listened to while playing them.

For instance, there's a scene where Margaret and classmates are at a party and someone shouts, "Let's play a game," after which the camera immediately flashes to an empty bottle lying on the floor. The idea behind that editing choice — and there are many similarly clever moments in writer/director Kelly Fremon Craig's film — is to provoke nostalgia in adults who remember exactly what that bottle means, rather than to introduce the game to children who may not play "Spin the Bottle."

Maybe kids will take their parents to "Are You There God?" and vice versa? I hope so. It was made with care, humor and compassion and if those things guaranteed success at the multiplex, it would be a smash.

'Are You There God? It's Me, Margaret.'

***1/2 out of 4 stars