Winona Ryder acquired the rights to the novel herself and then spent seven years trying to get the movie made.
Angelina Jolie avoided any communication with Winona Ryder when making the movie, claiming that if she saw anything human about Ryder, she would not have been able to act out the sociopath character Lisa Rowe as effectively.
Much of the movie was filmed at the Harrisburg (Pennsylvania) State Hospital. The hospital was still in use for treatment of mentally ill patients, until closed down in 2006.
The book and the movie Girl, Interrupted (1999), take their title from the painting "Girl Interrupted at her Music" by Dutch painter Johannes Vermeer.
The ice cream parlor the girls visit is "Eckel's Ice Cream Fountain" in Mechanicsburg, Pennsylvania. The store even has a "Girl, Interrupted" sundae. As of 2024, the parlor is still in operation.
Henry Alex Rubin: The guy who first starts dancing with Susanna Kaysen at the post-graduation party.