Lee is a highly observant working-class teenager from South Bend, Indiana, who attends the prestigious Ault prep school on a scholarship. She feels entirely out of place among her affluent classmates and constantly monitors her social standing. Her self-consciousness drives her to construct a new identity for the boarding school environment, often causing her to push away her family and her own interests in pursuit of acceptance.

Cross is the most popular boy in Lee's grade and a talented basketball player. He moves comfortably through Ault's elite culture without seeming overly arrogant. Though he participates in typical teenage boy behavior, he occasionally surprises his peers with his independence and direct communication.

Martha becomes Lee's best friend and roommate starting in their sophomore year. She serves as a dependable presence in Lee's life, offering straightforward advice instead of participating in petty gossip. She lacks the calculated cruelty of many other Ault students and acts as a stabilizing force.

Sin-Jun is an international student whose father owns several running shoe factories overseas. She initially appears quiet as she handles the intense social and academic pressures of the boarding school. Her quiet exterior hides a much more assertive personality that emerges as she settles into Ault.

Terry is Lee's father, a working-class man who owns Mattress Headquarters in South Bend, Indiana. He is blunt and relies heavily on bawdy humor to connect with people. Though he loves his daughter deeply, his unpolished demeanor clashes sharply with the refined atmosphere of Ault, causing severe tension.

Lee's mother is a former bookkeeper who maintains a sincere connection with her daughter. She generally yields to her husband's lead in social situations but displays quiet agency in how she cares for Lee, writing her letters and discussing personal matters.

Conchita is an incredibly wealthy student whose father is an oil baron and whose mother is Mexican. Because of her asthma, Ault grants her a massive, specially decorated room with a private phone. She initially bonds with Lee over music but struggles to maintain the friendship when social circles shift.

Aspeth is the acknowledged queen of Lee's class, functioning as a wealthy and frequently acerbic girl who commands attention. She dictates social trends effortlessly and often engages in the mean-girl dynamics that define Ault's hierarchy.

Dede is one of Lee's freshman-year roommates, characterized by her frequent anxieties and her intense worship of popular girls. She is desperate to fit in with the ruling crowd and frequently acts as Aspeth's loyal follower, sometimes clashing directly with Lee.

Little is a Black scholarship student from Pittsburgh who excels at cross-country and basketball. She views the affluent culture of Ault with open scorn and actively rebels against the wealthy student body. She finds Lee to be one of the few genuine people on campus.

Gates is Ault's first female senior prefect, hailing from a farm in Idaho. She is tall, attractive, and holds significant authority among the student body. Her early kindness makes a strong impression on the isolated freshman Lee.

Clara is a self-assured student who becomes Sin-Jun's roommate during their sophomore year. Unlike many girls at Ault, Clara does not seem insecure about her body and frequently hums or sings to herself, maintaining her confidence despite the judgmental atmosphere.

Aubrey is a small, freckled freshman who works earnestly to tutor Lee in math. Despite Lee's tendency to get distracted by Ault's social drama during their sessions, Aubrey remains a dedicated and encouraging academic guide with a quiet affection for her.

Ms. Moray is a young replacement English teacher from the Midwest who earnestly tries to connect with her students. Her cheerful, motivational teaching style often clashes with the cynical and privileged attitudes of the Ault students.

David is a twenty-one-year-old local resident who works on Ault's kitchen staff. He attempts to strike up a friendly connection with Lee, but his working-class status makes Lee highly self-conscious around her peers, causing her to freeze him out.

Darden is a popular Black student from the Bronx who plays basketball. He moves through the predominantly white, affluent world of Ault with a careful awareness of his social standing, maintaining a cool and collected demeanor.