In Jerry Spinelli's Stargirl, conformity is a central theme. When Stargirl, an unusual free spirit, is the new girl at an Arizona high school, the gossip begins immediately. Students are confused by her name, her clothes, and where she apparently comes from. When the book's narrator, Leo Borlock, hears of Stargirl, he is told she was homeschooled. He responds, "Maybe that explains it." Before Stargirl even has the opportunity to talk or express herself with anyone, students have already made assumptions. Spinelli is conveying that conformity is the absence of individuality. Stargirl is different, and therefore, she makes people uncomfortable and is ostracized.
In addition to discussing the consequences of being different, Spinelli shows where conformity comes from. After Leo and Stargirl's relationship develops, they fight about what is socially appropriate. Leo explains that Stargirl's behavior is unusual. She asks why, to which he has no answer. He doesn't have an explanation until he states on page 137,
The point is, in a group everybody acts pretty much the same, that's kind of how the group holds itself together.
Spinelli is implying that to preserve the integrity of a group, there need to be rules. If the rules are broken, the group is lost, or the person responsible can no longer be a part of the group. Conformity, unlike individuality, is organized and easy to enforce.
After Leo and Stargirl discuss what she's doing wrong and that nobody likes her, she becomes Susan. Leo falls in love with Susan's "normal" look, expressing on pages 139,
She looked magnificently, wonderfully, gloriously ordinary.
Both Leo and Susan are happy with the change until it becomes clear that the other students still don't like her. Spinelli here is addressing the dangers of conformity. Stargirl temporarily loses her identity, Leo loses Stargirl, and the rest of the students continue to believe conformity is best—that is, until the novel's end. Spinelli's overall message is to be yourself and not care about the conformist opinions of others.