Pathological dissociation is highly associated with an antecedent history of maltreatment or other severe trauma and predictive of subsequent psychopathology, particularly development of posttraumatic stress disorder (PTSD). This project has been involved in the development and meta-analysis of measures to detect and quantify pathological dissociation. Recent contributions have involved the use of taxometric statistical procedures to refine a previously developed dissociation measure, the Dissociative Experiences Scale (DES). This refined version, the DES-T, has been adopted by several twin studies to determine the heritability of dissociative tendencies as well as by PTSD researchers. This project has also extended the DES assessment model to adolescents with the development of the A-DES version for measurement of dissociation in adolescents.