Melchior is an intelligent, highly ranked teenage student in a provincial German town. Unlike his peers, he has researched human reproduction and approaches puberty with intellectual curiosity rather than shame. He reads texts like Goethe's Faust and openly questions the rigid morals of the adults around him. He takes it upon himself to help his friends understand the physical changes they are experiencing.

Moritz is a fifteen-year-old student overwhelmed by academic pressure and his newly developing physical desires. He views his own puberty with deep shame and confusion, completely lacking the vocabulary to understand his body. Terrified of failing his exams and disappointing his parents, he lives in a constant state of anxiety.

Wendla is a fourteen-year-old girl maturing physically but kept completely ignorant about reproduction by her conservative mother. She possesses a natural curiosity and a desire to experience extreme human emotions, frequently expressing frustration at her sheltered life. Her innocent questions about where babies come from are met with fables about storks.

Hansy is a teenage student overwhelmed by his developing sexuality. He attempts to manage his physical urges by obsessively locking himself in bathrooms with art reproductions, particularly Palma Vecchio's Venus. He experiences a cycle of intense desire followed by crushing guilt over his actions.

Mrs. Bergmann is Wendla's mother, a conservative woman terrified of her daughter growing up. She attempts to protect Wendla through willful ignorance, telling her stories about the stork and refusing to explain human biology. Her parenting style is driven by a strong desire to maintain social respectability.

Fanny Gabor is Melchior's mother, who prides herself on her progressive approach to parenting. She allows her son to read challenging literature but struggles when the realities of raising a teenage boy test the limits of her open-mindedness. She attempts to offer practical advice to her son's distressed friends.

Ilse is a young woman who previously attended school with the main characters before leaving their provincial town. She now lives in the city, working as a model and sex worker for a bohemian group of painters. She represents a complete rejection of the strict moral codes that govern the other teenagers.

The Masked Man is a symbolic entity who intervenes during a critical juncture. He represents reason, personal agency, and the transition into adulthood. He challenges fatalistic attitudes and urges the younger characters to take responsibility for their choices rather than succumbing to despair.

Martha is a teenage schoolgirl who suffers severe physical abuse at the hands of her parents. She shares her grim home life with her friends, expressing a dark resignation about her situation. Her mistreatment provides a sharp contrast to Wendla's sheltered upbringing.

Thea is a young schoolgirl and part of Wendla's close circle of friends. She participates in their innocent discussions about marriage, children, and their peers, representing the typical, uninformed teenage girl in their restrictive society.

Ernst is a schoolboy who experiences the same academic pressures as his peers but manages to maintain a passing rank. He harbors dreams of becoming a respected reverend and living a quiet, domestic life.

Mr. Gabor is Melchior's father, representing the uncompromising, authoritarian attitude of the town's adult men. He believes in strict discipline and swift punishment to maintain a spotless social reputation, frequently clashing with his wife's parenting style.

Mr. Stiefel is Moritz's demanding father. He places impossible expectations on his son's academic performance, believing that educational failure is a supreme moral disgrace. His lack of empathy contributes directly to his son's overwhelming anxiety.

Headmaster Hart-Payne is the strict leader of the boys' school. He utilizes convoluted administrative language to justify his cruel policies and actively seeks to protect the institution's reputation at the expense of his students' well-being.

Reverend Bleekhead is the local clergyman whose sermons focus heavily on rigid moral conformity. His harsh, unforgiving interpretation of religion draws sharp criticism from intellectually rebellious youths.

Ina is Wendla's married older sister. Her recent childbirths are used by her mother as opportunities to perpetuate fables about storks, keeping the younger generation ignorant about physical intimacy.