Dissociative identity disorder, also known as polyphasic personality disorder, is a condition in which two or more identities or personalities control an individual’s behavior and is accompanied by episodes of amnesia. It is also called dissociative personality disorder in some publications. It is a type of mental illness that is classified in the Diagnostic and Statistical Manual of Mental Disorders (DSM) as an Axis I dissociative disorder. The diagnostic criteria for DID in the Diagnostic andStatisticalManualofMentalDisorder (DSM I 1V) are as follows: 1. At least two identities or personality states repeatedly control the patient’s behavior. 2, These disorders are not due to the direct physiological effects of the substance (e.g., temporary loss of consciousness or disorganized behavior in alcohol intoxication) or general medical conditions (e.g., complex partial seizures). 3. The presence of two or more distinct identities or personality states (each with its own relatively enduring perceptions, connections, and ways of thinking about the environment and oneself). 4. Inability to recall important personal information to a degree that cannot be explained by usual amnesia.