Widely regarded as the definitive reference, this handbook brings together foremost authorities on posttraumatic stress disorder (PTSD). Diagnostic, conceptual, and treatment issues are reviewed in depth. The volume examines the causes and mechanisms of PTSD on multiple levels, from psychological processes to genes and neurobiology. Risk and resilience processes are addressed across development and in specific populations. Contributors describe evidence-based assessment and treatment approaches as well as promising emerging interventions.