It was a shock for 11-year-old Margaret when she got home from summer camp to discover that Mom and Dad rented out their New York City apartment and bought a house in Farbrook, New Jersey. Margaret figures this is because her parents think Margaret’s Grandma, who lives in the city, has too much influence over Margaret.
Hours after moving in, a girl named Nancy invites Margaret to play in the sprinklers. She watches Margaret change into a swimsuit and remarks that Margaret’s chest is still flat. The girls’ fun in the sprinkler comes to an end when Nancy’s older brother Evan and his friend, Moose, turn the sprinkler on full blast. As Nancy walks Margaret home, she invites her to join her secret club and tells Margaret not to wear socks on the first day of school—if she does, everyone will think she’s a baby. That night, Margaret asks God to help her grow breasts. Her parents don’t know she talks to God, so she only does so privately.
On the first day of school, Margaret and Nancy learn they have a first-year teacher, Mr. Benedict. After school, Margaret goes to Nancy’s first secret club meeting. She meets the other two girls, Gretchen Potter and Janie Loomis. They decide they all have to wear bras, keep a Boy Book (a ranked list of boys they like), and share immediately if they start their period. Nancy also tells Margaret about Laura Danken, their classmate who is physically very mature. According to Nancy, Laura regularly lets Moose and Evan touch her. Margaret tells her friends about how her mom’s parents disowned her mom when she married a Jewish man (Margaret’s dad). This is why her parents are raising her without religion; she can choose a religion for herself when she gets older if she wants. Nancy is aghast, since everyone in Farbrook either joins the Y or the Jewish Community Center, depending on their religious affiliation. Over the weekend, both Janie and Margaret buy their first bras.
On Monday, Mr. Benedict assigns a yearlong personal project. Students can study whatever they want, however they want. At the secret club meeting, the girls decide the project is silly. They check each other’s bras, perform an exercise to help them grow breasts, and Nancy looks through the Boy Books. Except for Margaret, who put Jay Hassler first, they all put Philip Leroy first. Margaret actually has a crush on Moose, but she’s not going to admit it because Nancy hates him.
Margaret decides to do her project for Mr. Benedict on religion—she’ll study different religions and decide what she is at the end of the year. She asks Grandma if she can accompany her to temple and Grandma is ecstatic. They go for Rosh Hashanah. Margaret loves the music, but she doesn’t understand much of the service—especially the bits in Hebrew. She doesn’t feel God while she’s in the temple, either, but she continues to talk to him at night.
As fall turns to winter, Margaret accompanies Janie to church (which seems the same as temple, except that the service is all in English) and the PTA puts on a square dance for the sixth graders. Margaret is excited to dance with Philip until she discovers that like most of the boys, he steps on the girls’ feet. In December, Margaret and her friends look through an anatomy book and one of Margaret’s dad’s Playboy magazines—they think naked men look weird, and Nancy in particular wants to look like the women in Playboy. Margaret also discovers that Mom sent a Christmas card to her estranged parents.
Just after winter break starts, Margaret gets an invitation to a party at Norman Fishbein’s house. Margaret spends the day of the party preparing for her big night. She stuffs her bra with six cotton balls and asks God to help her grow breasts. At the party, the kids play Spin the Bottle and Two Minutes in the Closet. Margaret kisses Philip and Norman during the games, and she thinks Laura seems oddly nervous for being so promiscuous. Over the break, Margaret also goes with Nancy’s family to their Christmas Eve church service. Margaret loves the music, but she doesn’t feel closer to God in the church.
In January, Grandma heads to Florida and Margaret and her female classmates see a movie in school on menstruation. Margaret already knows everything, and she resents that the movie is basically an advertisement for Secret Lady brand period products. A week later, Gretchen gets her first period. When Margaret tells Mom about Gretchen, Mom shares that she didn’t start her period until she was 14. Margaret is terrified that she won’t start her period and won’t be normal. She’s even more distraught when, a few weeks later, Nancy reveals that she started her period. Margaret begs God to help her be normal.
In March, Grandma invites Margaret to visit her in Florida over spring break, and Margaret accompanies Nancy’s family and Moose on a day trip to New York City. Margaret is thrilled to be out with Moose, but it’s a shock when Nancy starts her period—and Mrs. Wheeler reveals that it’s Nancy’s first period. Apparently, she had lied before. It’s Margaret’s 12th birthday a week later. Mom agrees to buy Margaret deodorant to mark the occasion. The day seems to be going well until Mr. Benedict announces a group project—and reveals that he already chose students’ groups. Margaret will be working with Laura, Philip, and Norman. She’s in a bad mood for the entire three weeks of the project.
Things come to a head one afternoon when Margaret and Laura work after school in the library. Laura is planning to go to confession after she’s done. Margaret is so busy wondering if Laura tells the priest about all her sexual exploits that she copies verbatim out of the encyclopedia. When Laura calls her out on this, Margaret insults her for being promiscuous. Laura leaves the library, angry and upset. She asks Margaret to consider how horrible it is to be picked on for being the most developed kid in class, and she implies that there’s no truth to Margaret’s accusations. Feeling awful, Margaret decides she’d better confess, too—but she doesn’t know how, and she leaves the church in tears. She also realizes Moose might be lying about Laura to make himself look better.
A week before Margaret is set to visit Grandma in Florida, Mom gets a letter from her parents, Margaret’s Grandmother and Grandfather. They’re coming to visit over spring vacation, so Margaret can’t go to Florida. Margaret is incensed; God must be punishing her for being mean to Laura. The visit is awful. When Grandmother and Grandfather try to insist that Margaret is a Christian and should go to church, Mom and Dad insist that Margaret can choose. To escape her grandparents, Margaret goes with Janie to the movies the next day. They decide to buy pads at a drugstore, just in case either of them starts their period. When Margaret gets home, Grandmother and Grandfather announce they’re leaving early. Once they’re gone, Margaret practices wearing a pad. That night, Grandma and her new boyfriend, Mr. Binamin, show up on the doorstep. Grandma explains that she came hoping to tell Mom’s parents that Margaret is Jewish. Margaret snaps. She insists she doesn’t believe in God. She and God aren’t speaking anymore.
To finish her project for Mr. Benedict, Margaret writes him a letter detailing her experiences at church, temple, and confession. She admits that she doesn’t know what religion she is—or if she wants to choose—but she does know that if she has kids, she’s going to tell them what religion they are. Trying to figure it out later in life is too hard.
School lets out in June. Hearing Moose mowing the lawn outside, Margaret decides to confront him about telling lies about Laura. But as Margaret confronts him, she realizes Nancy probably started the lies about Laura. This makes Margaret feel better about her crush on Moose. She goes to the bathroom and discovers she started her period. Margaret thanks God for helping her.
