DissociativeIdentityDisorder (DID), previously known as MultiplePersonalityDisorder (MPD), is also referred to as 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 andStatisticalManualofMentalDisorder(DSM1V) contains the following criteria for the diagnosis of DID: 1. The existence of two or more distinct identities or personality states (each with its own relatively enduring perceptions, connections, and ways of thinking about the environment Each has its own relatively enduring perceptions, connections, and ways of thinking about the environment and itself). 2. At least two identities or personality states repeatedly control the person’s behavior. 3. The inability to recall important personal information to a degree that cannot be explained by the usual amnesia. 4. The impairment is not due to the direct physiological effects of the substance (e.g., temporary loss of consciousness or confused behavior in alcohol intoxication) or to a general medical condition (e.g., complex partial seizures).