Papers in this special issue of the Journal of Anxiety Disorders concern critical issues and core assumptions that underlie the diagnostic construct of posttraumatic stress disorder. Rather than addressing specific points raised in these papers, we consider the issues and their implications for redefining PTSD and associated disorders in the DSM-V. Specific proposals are advanced to tighten definitional criteria for traumatic events and posttraumatic symptoms. We believe the more stringent criteria express the intent of the PTSD category and will promote more effective research on whether that intent was legitimate or based on misconceptions.