In The Face on the Milk Carton by Caroline B. Cooney, the protagonist Janie Johnson undergoes many changes from the beginning to the end of the story, both in terms character development and the actual circumstances of her life.
The book starts out showing Janie as a typical suburban teenager. She is fifteen when the story begins. Her primary concerns are whether the boy she likes will ask her out, whether her life is exciting enough—she changes the spelling of her name to appear more exotic—and whether she will do well in school. In fact, her biggest problem with the story begins is that she, like many other teens, wants to learn to drive now that she is old enough to get a learner’s permit, but her parents are not being as helpful as she would like.
Over the course of the story, Janie learns things about herself and matures. The issues she encounters also cause actual changes in her family structure. At lunch one day, Janie notices the eponymous face on the milk carton and sees similarities between herself and the child pictured on the carton. This is the catalyst for Janie to begin questioning everything about her seemingly happy existence. In doing so, she comes to know her parents better and develops a deeper relationship with them that is built on honesty. Her relationship with Reeve also grows over the course of the story, as she confides in him and shares extremely personal thoughts and feelings.
As she matures, she also develops more courage than she might have had at the beginning of the story. At the end, when her mother telephones Janie’s biological family and passes the phone receiver to Janie, the implication is that Janie is now mature enough to deal with this extremely complicated and sad set of circumstances.