The book contains many references to real people and events in Plath's life. Plath's magazine scholarship was at Mademoiselle magazine beginning in 1953. Philomena Guinea is based on author Olive Higgins Prouty, Plath's own patron, who funded Plath's scholarship to study at Smith College. Plath was rejected from a Harvard course taught by Frank O'Connor. Dr. Nolan is thought to be based on Ruth Beuscher, Plath's therapist, whom she continued seeing after her release from the hospital. A good portion of this part of the novel closely resembles the experiences chronicled by Mary Jane Ward in her autobiographical novel The Snake Pit; Plath later stated that she had seen reviews of The Snake Pit and believed the public wanted to see "mental health stuff," so she deliberately based details of Esther's hospitalization on the procedures and methods outlined in Ward's book. Plath was a patient at McLean Hospital, an upscale facility which resembled the "snake pit" much less than wards in the Metropolitan State Hospital, which may have been where Mary Jane Ward actually was hospitalized.
In a 2006 interview, Joanne Greenberg said that she had been interviewed in 1986 by one of the women who had worked on Mademoiselle with Plath in the college guest editors group. The woman claimed that Plath had put so many details of the students' lives into The Bell Jar that "they could never look at each other again," and that it had caused the breakup of her marriage and possibly others.
Janet McCann links Plath's search for feminine independence with a self-described neurotic psychology. Plath's husband has at one point insinuated that The Bell Jar might have been written as a response to many years of electroshock treatment and the scars it left.