Abby Ryder Fortson, Amari Price, Elle Graham and Katherine Kupferer in “Are You There God? It’s Me, Margaret.” Dana Hawley/Lionsgate

For readers of a certain demographic – say, 46-year-old white women – there were three sacred texts of pre-adolescence. First were the “Babysitters Club” books, through which we came to envy girls with private phone lines and learn about diabetes. Second was the “Sweet Valley High” series, through which we came to envy the Wakefield twins’ figures – perfect size 6s, as we were reminded in every book – and learn that the possibility of getting kidnapped was very real. But the holiest of holies were the works of Judy Blume, who taught us that people with seemingly enviable lives had problems of their own. It was through her books that we learned about ourselves.

Blume’s seminal 1970 novel, “Are You There God? It’s Me, Margaret,” is only now – finally – getting the cinematic treatment. (A runner-up for Blume’s best book would be 1975’s “Forever,” which was secretly passed around nearly every elementary school, simultaneously demystifying sex and ruining the name “Ralph” for a generation.) Today, many of her first preteen readers now have Margarets of their own. This new film speaks to both generations with wit and compassion.

The movie follows the book fairly faithfully (or as faithfully as this 46-year-old brain can remember). Margaret (Abby Ryder Fortson of “Ant-Man and the Wasp”) has just returned from summer camp to find that her parents (Rachel McAdams and Benny Safdie) have decided to move from New York to New Jersey, a choice both Margaret and her grandmother (Kathy Bates) think is a huge mistake, one that will ruin Margaret’s life.

Once ensconced in suburbia, Margaret is befriended by Nancy (Elle Graham), the one girl in the class who seems to intuitively know exactly how to be the “right” kind of girl. With two other girls, Nancy and Margaret form a secret club with a focus on boys, bras – and how to best fill them – and getting their first periods. Margaret, on her own, struggles with religion: Her Christian mother and Jewish father – both nonobservant – have decided to allow Margaret to choose her faith, if she chooses any at all. In this story, however, spirituality takes a back seat to learning how to wear a maxi pad and undertaking breast-enhancing exercises, accompanied by the chant, “We must, we must, we must increase our bust.” In one small update that’s also reflected in modern versions of the book, belted pads have been replaced with the (still-awful) diaper-thick adhesive pads of those dark ages.

Rachel McAdams, left, and Abby Ryder Fortson in a scene from “Are You There God? It’s Me, Margaret.” Dana Hawley/Lionsgate via AP

“Margaret” is thoroughly anchored in the ’70s – and has the fantastic needle drops to prove it – and yet the story will still resonate, both for those who read the book decades ago and for the 11-year-old girl in the next seat. A party featuring Spin the Bottle and Seven Minutes in Heaven is so true to life, you can almost smell the pungent aroma of adolescent cringe sweat, Sea Breeze astringent and Brut cologne. In a welcome change from the book, both Margaret’s mother and grandmother get their own small subplots. McAdams uses hers to remind us that just because you get older doesn’t mean you have all the answers. The awkwardness of your teen years doesn’t vanish; behind every lived-in face is the girl you once were.

Filmmaker Kelly Fremon Craig (writer and director of the wonderful teen comedy “The Edge of Seventeen”) finds the humor in adolescence without ever mocking her heroine. The film’s laughs come from empathy, not derision, when a brassiere saleswoman tut-tuts that Margaret is “not even a 32A.” (Remember when not needing a bra in sixth grade was just as bad as needing one in fourth?) We giggle and cringe, but this time we have the advantage of hindsight: If we made it through all this, then Margaret can, too.

“Are You There God? It’s Me, Margaret” is decidedly and joyfully innocent. It’s refreshing to see a story about tween girls who are not depicted as children or shamed or sexualized. Things were simpler in the 1970s: no social media, no cellphones, nary a computer to be seen, and yet this story still rings true to modern-day Margarets, regardless of their current age.

Whether you’re coping with hot flashes, acne or both – come on, Mother Nature, not cool! – “Margaret” reminds us that this too shall pass, and that we are not alone. Those who are anxiously awaiting the arrival of their periods and those who are wishing that it would just stop already will find common ground in Margaret’s story. It seems that Blume’s work can still teach us a few things about ourselves.