- Deborah is the protagonist of I Never Promised You a Rose Garden.
The novel chronicles her three-year battle with schizophrenia in mental hospital. With the help of her dedicated therapist, Dr. Fried, Deborah finds the courage to emerge from the Kingdom of Yr, a world Deborah created as a defense against a confusing, frightening reality.
- Esther Blau is Deborah's mother. During the course of the novel, she comes to terms with her daughter's illness. Her strength, faith, and love in her daughter helps her insist that Deborah continue receiving treatment even when she seems to show few signs of improvement or recovery.
- Jacob Blau is Deborah's father. He feels alternately guilty and angry at Deborah's condition. Over the years, he has had financial difficulties, forcing him to live on the charity of is in-laws. During Deborah's treatment, Esther realizes that she always placed Jacob's wishes second after her father's.
- Suzy Blau is Deborah's younger sister. Esther and Jacob do not tell her the truth about Deborah's illness until it becomes clear that there is no quick and easy cure. Although she loves Deborah, Suzy feels neglected because she often has to arrange her life around the whims of her older sister's illness.
- Esther's parents are wealthy first generation Jewish immigrants. Esther's father, a Latvian immigrant with a clubfoot, has been driven by anger and resentment for all of his life. The old insults of a long-dead Latvian nobleman continue to drive his ambition to build a wealthy dynasty in the United States.
Dr. Clara Fried
- Dr. Clara Fried is Deborah's famous German therapist. Although it means she will have to decline several other professional opportunities, Dr. Fried takes on Deborah's case. Her empathy is arguably her greatest gift as a doctor. With her help, Deborah gains to courage to fight her way to mental health.
Miss Coral Allen
- Miss Coral Allen is a well-educated, elderly mental patient at Deborah's hospital. She teaches Deborah everything she knows about Latin and Greek.
- Carmen is briefly a patient at Deborah's hospital. Her multimillionaire father takes her out of the hospital before she can receive treatment. Shortly thereafter, she commits suicide. After she hears the news, Deborah realizes that her parents allowed her to stay even when there were few signs of recovery for a long while.
Claude and Natalie
- Claude and Natalie are Esther's siblings.
- Quentin Dobshansky is one of the attendants at the mental hospital. It pains Deborah that he is nervous around her sometimes because she has a mental illness.
- Ellis is a Conscientious Objector. When given a choice between prison and working in the mental hospital, he chooses the hospital. He is the replacement for Hobbs, an attendant who commits suicide during the course of the novel. Ellis's fear and hatred of the mental patients is evident in his every gesture. The patients, sensing that Ellis himself has mental problems, torment him by ridiculing his fundamental religious beliefs. McPherson, another attendant, convinces Deborah and the other patients to stop tormenting them. Later, Deborah witnesses Ellis physically abuse Helene, but no one takes her seriously when she reports it.
- Eugenia and Deborah became friends because they attended the same summer camp when they were children. One day, Deborah found Eugenia naked in the camp bathroom. She gave Deborah a belt and asked Deborah to beat her. Deborah refused and never spoke to Eugenia again.
- Mrs. Forbes is an attendant at the hospital. She is well liked by the patients, so they try to protect her from harm. However, Miss Coral breaks her arm by throwing a bed at her during a psychotic episode.
- Halle is a well-liked doctor at the mental hospital. When Carla and Deborah escape from the hospital on a lark, he decides not to punish them upon their return because he is pleased that they had fun.
- Helene is a well-educated patient at the hospital. She is prone to frequent violent psychotic episodes. During one such episode, she breaks a tray over Deborah's head. Afterwards, Deborah is angry that everyone rushes to contain Helene, but no one bothers to check on her, the victim.
- Hobbs is an attendant at the hospital. Sensing that Hobbs also suffers from mental problems, the patients torment and abuse him. Hobbs eventually commits suicide and is replaced by Ellis, a Conscientious Objector.
- When Deborah enters her third year of treatment, she requests permission to live in the town near the hospital as an outpatient. She rents a room from Mrs. King. Mrs. King has not lived in the town long enough to acquire the fear and contempt that the other residents feel toward the outpatients from the hospital.
- Dr. Lister is the Blaus' family physician. Esther and Jacob put Deborah in the mental hospital at his recommendation.
- McPherson is a well-liked attendant at the hospital. He convinces Deborah and the other patients to stop tormenting Ellis.
- Lee Miller is one of the patients at the mental hospital. When the normally silent Sylvia speaks, Lee hurries to inform the medical staff. Deborah admires her for having the courage to participate in reality for Sylvia's benefit even though Sylvia will probably not thank her for it.
- When Deborah arrives at the hospital, Doris Rivera is a legend because she managed to leave the hospital to live a normal life in the outside world. Her success frightens the patients because they fear that they might one day have to try to live in the outside world, too. When Doris is re-committed to the hospital, the other patients are also bitterly disappointed because they secretly hope they can get well despite their fears.
- When Dr. Fried leaves the hospital during one summer, Dr. Royson takes over Deborah's case temporarily. He and Deborah do not get along because he focuses on trying to logically prove to her that Yr is Deborah's own creation, not a real kingdom.
- Carla Stoneham is a patient at the mental hospital. When Carla was young, her mother shot Carla, Carla's brother, and then herself. Only Carla survived. Over the course of their three years at the hospital together, she and Deborah become friends.
- Sylvia is a patient at the mental hospital. She is normally silent and withdrawn. When Helene attacks Sylvia in a fit of violence, Sylvia makes no outward sign of distress. While the staff rushes to contain Helene, only Deborah understands why Sylvia needs attention as much as Helene. The same thing happened when Helene attacked Deborah. Deborah wants to offer Sylvia comfort, but she can't bring herself to do it.
- Tilda is one of Dr. Fried's former patients. Dr. Fried treated her in Nazi Germany before immigrating to the United States. Tilda once escaped the hospital, only to return to tell Dr. Fried that the outside world was crazier than the one inside the hospital.
Dr. Dowben, Dr. Fiorentini, Dr. Adams, Dr. Craig, Dr. Venner, Dr. Hill, Dr. Ogden, Dr. Oster
- These individuals all work as doctors at the mental hospital. They have widely varied relationships with the patients, some more understanding and empathetic than others.
Constantia, Miss Cabot, Mary, Linda, Marion, Sue, Marie, Lena, Lucia, Della, and Lucy
- These individuals are patients in the mental hospital.
- Anterrabae, or the Falling God, is the most powerful being in the Kingdom of Yr, a world that Deborah created as a defense against a confusing and frightening reality.
- The Censor is a being in the Kingdom of Yr, a world that Deborah created as a defense against a confusing and frightening reality. Once, Deborah accidentally left a clue in the real world to the existence of Yr, so the gods of Yr created the Censor to guard Yr's secrets from Earth. Over time, the Censor has become a tyrant who watches and controls all of Deborah's actions to prevent her from revealing Yr's existence.
- The Collect is the chorus of voices that constantly criticize Deborah in Yr. The Collect represents all the teachers, peers, and neighbors who abused and insulted Deborah throughout her childhood and adolescence.
- Idat, the Dissembler, is a beautiful goddess in Yr, a world Deborah created as a defense against a confusing, frightening reality.
- Lactamaeon is the second most powerful god in Yr, a world that Deborah created as a defense against a confusing, frightening reality.