After the holiday vacation begins, Margaret receives an invitation in the mail for Norman Fishbein's party. A few minutes later Nancy calls, and confirms that the entire class is invited to the party. The girls take this new event very seriously, and plan to wear their best party clothes. Margaret's opinion of Norman improves drastically as she gets excited about the party. While preparing, she takes a moment to look at herself naked in the mirror, and she asks God to help her grow more because she still feels like a little girl. Finally, she decides to stuff a few cotton balls into her bra to make her chest look bigger.
At the party, Nancy introduces Margaret to Norman's mother, and the girls then go to the basement with everyone else. Most of the class is there. For the most part, the boys and girls remain separated on opposite sides of the room. Everyone behaves very well until some of the boys decide to blow mustard through straws at the ceiling, which annoys Mrs. Fishbein. Nancy and another boy, Freddy Barnett, also get into a small fight when Freddy makes fun of the girls, and he ends up tearing the pocket off Nancy's dress. When she learns of this altercation, Mrs. Fishbein gets even more aggravated and threatens to send all the students home, but after she walks back upstairs the kids simply laugh at her.
Norman then announces that it's time to play games, and the first game he suggests is Guess Who: in this game, the lights must be turned off and the boys must guess which girl is which based on the way the girls feel above the neck. The girls will absolutely not have this, however, so the class begins playing Spin the Bottle. Norman spins Janie and kisses her on the cheek, and Janie does the same for Jay Hassler but first misses his face. Gretchen gets Philip Leroy, who then gets Laura Danker.
After this, the students start playing Two Minutes in the Closet, and Norman calls Gretchen's number first; they return long before their two minutes are through. Freddy then calls Laura, and Laura calls Philip. Then, to Margaret's surprise, Philip calls her. He actually kisses her on the mouth twice, though the kisses are really fast. Margaret is in such a daze afterward that she accidentally calls Norman's number, but tells him to kiss her fast on the cheek. Later that night, when Nancy tells Margaret she's probably the luckiest girl in the world, Margaret gloats by saying that Philip kissed her five times or so.
On Christmas Eve, Margaret goes to church with the Wheelers—afterward, she comes home and talks to God, saying she still hasn't felt any sort of connection during public worship. She asks him to give her a hint about which faith she should choose. Margaret's family situation, however, is changing quickly. When Sylvia returns from her cruise, she moves to Florida, declaring that New York has nothing to offer since Margaret is gone.
When school begins again, the girls see a movie about menstruation in their gym class, and only a week later, Gretchen is the first of the PTS girls to get her period. She tells the girls everything she can about what it felt like and what she did. Margaret frets about not getting hers yet, and begs God to let her get it soon. When Nancy is on vacation, Margaret gets a postcard from Nancy saying she's gotten her period too, and Margaret gets even more upset.
The party described in these chapters is a very symbolic event for Margaret and her classmates; it's their first taste of the sophisticated adult world, where they have to present themselves as respectable, grown-up individuals rather than as misbehaving children. It is clear that they take the preparations for this occasion quite seriously: all the girls wear their best dresses and are extremely polite to Mrs. Fishbein. However, once the party begins, this sophistication is compromised by moments of obvious immaturity. They students blow mustard at the ceiling, fight, and make fun of each other. Overall, the dinner party is a good starting experience, but events show that the sixth-graders haven't quite grown up yet—after all, becoming mature take time.
At the party, Margaret passes an important milestone on the road to growing up: she has her first kiss. Of course, it's merely a peck and it's received while playing a game, so this kiss doesn't necessarily represent mutual feelings. Yet for a girl who is extremely concerned with falling behind her peers, this new development serves as a huge confidence boost. Philip Leroy, the boy at the top of all four of the PTS Boy Books, voluntarily kisses Margaret on the mouth; just like buying a bra for the first time, this is an important step that makes Margaret feel good about her progress.
Unfortunately, though, this high isn't fated to last. Shortly after Norman Fishbein's party, two of Margaret's friends get their first periods and Margaret feels far behind once again. The novel is filled with shifts and reversals such as this: one moment, Margaret experiences something that makes her feel grown-up, and the next moment she's reminded once again that she's still a child. The transition from childhood to adulthood is never smooth, and this frustrates Blume's young protagonist to no end. It doesn't help that Margaret constantly feels as though she needs to compare herself to everyone around her; this puts even more pressure on her to accomplish things that are far beyond her control.