Objective: This study addressed predictors of change in posttraumatic stress symptoms (PTSS) among youths who had experienced physical injuries. The influences of pretrauma internalizing and externalizing problems, prior stressor exposure, and gender were investigated. Additionally, gender was examined as a moderator of the associations between internalizing problems and PTSS, externalizing problems and PTSS, and prior stressor exposure and PTSS. Method: Participants were 157 children and adolescents (75% male; age M = 13.30 years, SD = 3.60; 44% Caucasian, 39% African American, 13% Hispanic, and 4% other) admitted to 2 hospitals for physical injuries. Youths and their parents completed measures of PTSS (Child Posttraumatic Stress Reaction Index), internalizing and externalizing problems (Child Behavior Checklist), and prior stressor exposure (Coddington Life Events Scale, Child) during the hospital stay; youths completed up to 3 additional PTSS assessments targeted at 3, 6, and 12 months postinjury. Results: Multilevel regression analyses revealed a significant average decline in PTSS over time (p less than 0.05) that followed a curvilinear trajectory. Externalizing problems, prior stressor exposure, and female gender predicted higher initial PTSS levels (p less than 0.05). Gender moderated the influence of internalizing problems, externalizing problems, and prior stressor exposure on decline in PTSS over time (p less than 0.05). Patterns of recovery for those with high and low levels of each characteristic differed for girls and boys. Conclusions: Findings suggest targets for clinical consideration, both with respect to identifying subgroups of children and adolescents that may warrant early assessment and monitoring and timing of more directed PTSS treatment intervention. (Contains 4 tables, 1 figure and 2 footnotes.)