We summarize recent research on the psychological processes implicated in posttraumatic stress disorder (PTSD) as an aid to evaluating theoretical models of the disorder. After describing a number of early approaches, including social-cognitive, conditioning, information-processing, and anxious apprehension models of PTSD, the article provides a comparative analysis and evaluation of three recent theories: Foa and Rothbaum's [Foa, E. B. & Rothbaum, B. O. (1998). Treating the trauma of rape: cognitive behavioral therapy for PTSD. New York: Guilford Press] emotional processing theory; Brewin, Dalgleish, and Joseph's [Psychological Review 103 (1996) 670] dual representation theory; Ehlers and Clark's [Behaviour Research and Therapy 38 (2000) 319] cognitive theory. We review empirical evidence relevant to each model and identify promising areas for further research.