This investigation examined psychosocial and behavioral factors involved in the course of post-traumatic stress disorder (PTSD) symptoms in youth affected by Hurricane Katrina. Participants (N = 152; 54% female; 61% Caucasian; mean age = 11.5 years) self-reported on hurricane exposure, PTSD symptoms, fear reactivity, regulatory abilities, social experiences, and coping 1.5 months following the storm, and on their PTSD symptoms again 8 months following the storm. Fear reactivity predicted more severe initial PTSD symptoms. Peer victimization added to the prediction of subsequent PTSD symptoms. Whereas regulatory abilities protected against PTSD symptoms both initially and across time, a negative coping style enhanced vulnerability to PTSD symptoms. Thus, mental health service providers should work to minimize peer victimization experiences, improve regulatory abilities, and promote alternatives to negative coping in youth following disasters. (Contains 7 tables and 2 figures.)