The present study describes posttraumatic stress reactions in young witnesses of motor vehicle accidents (MVAs). This study investigated (a) whether witnesses of MVAs report fewer trauma symptoms than direct victims, but more than adolescents who were never exposed to an MVA; and (b) whether individual differences in sex, negative appraisal, avoidant coping, and social support account for variability in trauma symptoms beyond status as a witness as compared to a victim. Self-report data came from a community-based sample of 3,007 adolescents with an average age of 14.6 years and comprising 53% boys. Compared to direct victims of an MVA in which someone was injured, witnesses of MVAs with injury reported significantly less internalizing symptoms, such as symptoms of posttraumatic stress (d = 0.25), fear (d = 0.21), and depression (d = 0.17). Compared to adolescents who were never exposed to an MVA with injury, witnesses reported significantly more externalizing symptoms (d = 0.24). In multiple regression analyses the significant difference between witnesses and victims disappeared when sex, other stressful events, appraisals, and coping were added to the model. These findings suggest that adolescent witnesses, as well as direct victims, may be at risk for posttraumatic reactions.