Book excerpt: Now in an extensively revised third edition with 65% new material, this is the authoritative reference on posttraumatic stress disorder (PTSD). Contributors examine the breadth of current knowledge on the mechanisms by which stressful events can alter psychological processes, brain function, and individual behavior. Risk and protective factors across development and in specific populations are explored. Reviewing the state of the science of assessment and treatment, the volume covers early intervention and evidence-based individual, couple/family, and group therapies. Conceptual and diagnostic issues are addressed and key questions for the next generation of researchers are identified. New to This Edition *Thoroughly revised to reflect the accelerating pace of scientific and clinical progress; includes a range of new authors. *Chapters on new topics: treatment of PTSD with comorbid disorders, and postmortem brain banking. *New chapters on previously covered topics, including DSM-5 and ICD-11 diagnostic criteria, the psychoneurobiology of resilience, and challenges in implementing clinical best practices. *New or updated discussions of such timely issues as treatment of refugees, telemental health, and technology-based interventions.