Margaret Simon is eleven, has just moved from New York City to New Jersey, and talks to God the way other kids talk to a diary: “Are you there God? It’s me, Margaret.” Kelly Fremon Craig, who wrote and directed, builds her adaptation of Judy Blume’s novel around that habit. Nothing grand happens to Margaret. The film is made of what she wonders about, and Fremon Craig is wise enough to leave it at that.

The book came out in 1970, and the film stays in that decade without winking at it. Margaret’s worries would be familiar to any sixth-grader today: whether her body will change on schedule, whether boys will notice her, which friends she can trust. Blume has said that Margaret is close, in body and in feeling, to the girl she herself was, and that her own relationship with God had little to do with organized religion. The film inherits that outlook. Margaret’s prayers are never a lesson to be delivered, and the story breathes on screen instead of ticking off chapters one by one.

Abby Ryder Fortson carries the picture. Her Margaret is curious and anxious in equal measure, and she makes the prayers sound like thinking out loud rather than recitation. Rachel McAdams plays Barbara Simon with a warmth that has a trace of worry underneath, and Benny Safdie is a gentle Herbert. Margaret’s parents come from different faiths, her mother Christian and her father Jewish, and she has been raised without a tie to either. That gap drives the whole story. A girl so willing to talk to God still feels she has no right to say which God she means.

Kathy Bates plays Sylvia, Margaret’s paternal grandmother, who hopes the girl will embrace Judaism and takes her to Rosh Hashanah services. Bates lets the hope show without leaning on it, and a little sharpness comes through as well. Margaret, meanwhile, is mostly watching, trying to work out whether she belongs to anything at all. For a school assignment she studies different beliefs and visits different places of worship. The film treats that search with respect rather than irony, and it never hands her a tidy conclusion.

The friendships are where the comedy lives. Nancy (Elle Graham) arrives sounding sure of everything, sex and kissing included, and Margaret is both overwhelmed and charmed by her. Being asked into a secret club thrills her. Together with Gretchen (Katherine Mallen Kupferer) and Janie (Amari Alexis Price), the two become the Pre-Teen Sensations, a club devoted to boys, bras and periods, all of which the girls wait for with a mixture of hunger and dread. They also chant “We must, we must, we must increase our bust!” while doing their exercises, and it is funny precisely because nobody in the room is joking. Underneath the swagger, they are scared. You can see it when Gretchen gets her first period and Margaret concludes that something must be wrong with her.

The film is at its sharpest about the way the girls turn that fear outward. Laura Danker, a classmate who has already started menstruating and wears a bra, is the one Margaret envies. Nancy claims Laura dates an older boy, and the Pre-Teen Sensations gossip about her letting boys touch her breasts. Then Margaret learns that Laura is a devout Catholic and is hurt by what has been said, and her guilt is believable because it arrives late, after the damage is done. I wanted more of this thread. Laura gets very little room, and a story so interested in how girls are judged by their bodies could have given her a fuller scene of her own. The same goes for some of the school material, which moves quickly and sometimes feels like a list of milestones rather than a stretch of days.

The party with Philip Leroy, built around a game of “two minutes in the closet,” gets the proportions right. A kiss is a big deal to Margaret and a small one to everyone else, and the film lets both be true.

Then comes Nancy’s lie. She has told the others she got her first period while away on vacation, and Margaret discovers the truth when Nancy gets her actual first period. The moment is awkward and oddly tender. Graham plays it without asking us to dislike her, which is generous of both the actor and the film.

Blume’s novel has been challenged over the years for its frank treatment of sexual and religious subjects. The film is gentler in manner and just as direct. Anyone who read the book at twelve will recognize it, and a viewer who has never heard of it can still follow every worry on screen. It is funny where Margaret is solemn, and serious where the jokes stop.