Wanda Petronski
Wanda Petronski is a quiet, socially outcast student who sits at the back of Room 13 until she stops coming to school. Wanda is the child of Polish immigrants and lives far from the school in an impoverished area called Boggins Heights. She never laughs, though she sometimes twists her mouth into a crooked smile. She wears the same faded blue dress to school every day, though she claims to own one hundred dresses at home. Peggy teases Wanda for saying she has a hundred dresses.
Peggy
Peggy is the most popular girl in school. She has pretty auburn curls, and is confident and talented. Peggy instigates the "hundred dresses game," in which she teases Wanda.
Maddie
Maddie, the book's protagonist, is Peggy's best friend. Maddie feels guilty for standing by and letting Peggy tease Wanda. Maddie herself is poor; she secretly wears Peggy's hand-me-down dresses.
Miss Mason
Miss Mason is the teacher in Room 13. Though she initially doesn't notice Wanda's absence, Miss Mason expresses regret when Wanda's father moves his family to the city, where they are less likely to encounter prejudice.
Bill Byron
Bill Byron sits in the seat behind Wanda. He has long legs, and likes to amuse other students in Room 13.
Willy Bounce
Willy Bounce is a student in Room 13. His surname is compared to Wanda Petronski's; both are considered humorous, but for different reasons.
Old Man Svenson
Svenson is an old man who lives near Wanda and her family in Boggins Heights. He lives alone with a cat and dog, and dresses all in yellow. Children walk quickly when passing his house.
Cecile
Cecile is a student in Room 13. She dresses in fine clothes and practices ballet. On the day the hundred dresses game begins, schoolgirls gather around Cecile to admire her new red dress.
Jake Petronski
Jake is Wanda's brother. To make money, he comes to school early to work as the janitor's assistant.
Jan Petronski
Jan is Wanda and Jake's Polish father. Jan writes a letter to Miss Mason to inform her that he is moving his family to the city, a more multicultural environment where his children won't encounter abuse because of their Polish surname.
