This article presents a reconceptualization of trauma in terms of the damage it inflicts on the patient's conception of his or her world. The article includes (1) an analysis of how this view renders the symptoms of posttraumatic stress disorder (PTSD) intelligible, (2) a demonstration of how it integrates research findings on who is most vulnerable to PTSD, (3) a critique of the currently dominant "reprocessing of maladaptive memory structures" accounts of how exposure therapy works, and (4) a reanalysis of how exposure therapies achieve their salutary results.