Preface: Sybil Summary and Analysis

This book is both a phenomenal case study and a moving narrative. The author spent ten years on the book; she interviewed Sybil and her therapist, Dr. Wilbur, researched personality disorder, and examined Dr. Wilbur's notes, Sybil's essays and diaries, and hospital records to gain and present an understanding of Sybil's condition. Hereditary, environment, parental relationships, and religious beliefs are shown to play a role in her severe disorder.

The author is adamant that the reader fully understands that Sybil's story is true and free from fabrications.