This discussion reinterprets a sixteenth-century case of possession and exorcism as Dissociative Identity Disorder (DID), formerly known as Multiple Personality Disorder (MPD). This is perhaps the earliest historical case in which DID can be diagnosed retrospectively with confidence. Jeanne Fery, a 25-year-old Dominican Nun, wrote her own account of her exorcism which took place in Mons, France in 1584 and 1585. Her exorcists produced an even more detailed account describing both identity fragmentation and a past history of childhood trauma. Also well described in both accounts are major criteria and associated features of DID as described in present day diagnostic manuals (American Psychiatric Association, 1987, 1994.) The 109-page description of her treatment course was republished in French in the nineteenth century by Bourneville (1886), a colleague of Janet, who also diagnosed Jeanne's disorder as "doubling of the personality," (the term then in use for DID). This article is the first English- language presentation of these documents. Previous studies have identified elements of identity fragmentation and possible childhood trauma in other possession cases from this era. For example, we have a detailed account of the 1623 investigation of Sister Benedetta, abbess of a Theatine convent in Italy (Brown, 1986). Benedetta was possessed by three angelic boys who would at times beat her causing chronic pain. These angels would also take over her body, each speaking a different dialect and producing specific facial expressions and tones of voice. Benedetta had amnesia for some acts done by these three, including a sexual relationship they initiated with a young nun in her charge. Associated features in this case included self-mutilation and disordered eating. However, Benedetta's case only hints at the presence of childhood trauma. Her parents were said to be possessed, too; her symptoms became uncontrollable after her father's death. She had been sent to the convent at age nine, the same age at which her sexually abusive alter, Splenditello, remained fixed. Jeanne Fery's case is not only earlier than Benedetta's but more complete. Her alter identities included Mary Magdalene, who was highly rational and helpful in her treatment, appearing at moments of crisis. This ego state might be described in twentieth-century terms as an internal selfhelper (Comstock, 1987). Several internal "devils" are described including Namon and Bélial, the latter attended by seven sub-entities representing the deadly sins. The devils are blamed for her acts of sacrilege but also function as protectors. A demon named Cornau ("Horns") is described as having seduced her with sweets at age four and seems to preside over her subsequent bizarrely disturbed eating. A demon named Sanguinaire de- mands pieces of her flesh, and this is how she explains her self-cutting. The devil Garga ("Throat") protected her from feeling the pain of beatings in childhood, but then reenacts these during her illness by head-banging, body-banging, and suicide attempts attacking the throat with cutting and self-strangulation. Jeanne's alters were at times visualized, at times heard arguing inside, and at times took over her body in violent pseudoseizures, rage attacks requiring restraints (from which she escaped), compulsive suicide attempts, regression to a childlike state, and episodes of prolonged sobbing and intense physical pain (especially headache). Sleep disturbance, abysmal sadness, conversion blindness, shivering, disordered eating, mutism, contorted facies, inexplicably lost and found objects, and episodic loss of knowledge and skills completed a clinical picture quite familiar to contemporary clinicians working with dissociative disorders.