The objective of this study was to investigate the cumulative effect of interpersonal and noninterpersonal traumatic life events (IPEs and nIPEs, respectively) on the mental health of adolescents and to determine if the adverse impacts of trauma were moderated by adverse family circumstances (AFC). Adolescents (mean age 16.7 years) from the normative population (n = 462) completed the questionnaire, the Linköping Youth Life Experience Scale (LYLES), together with Trauma Symptom Checklist for Children (TSCC). The lifetime accumulation of interpersonal, noninterpersonal, and AFC was independently related to trauma-related symptoms in both boys and girls. The number of AFCs moderated the mental health impact of both IPEs and nIPEs in boys but not in girls. Cumulative exposure to both interpersonal and noninterpersonal traumatic events is important for the mental health of adolescents, and, at least for boys, family circumstances seem to be relevant for the impact of trauma. Our results suggest that broader approaches to the study, prevention, and treatment of trauma, including consideration of cumulative exposure, different types of trauma, and additional social risk factors, could be fruitful.