ABSTRACT: Studies in Afghanistan have shown substantial mental health problems in adults. We did a survey of young people (11-16 years old) in the country to assess mental health, traumatic experiences, and social functioning.In 2006, we interviewed 1011 children, 1011 caregivers, and 358 teachers, who were randomly sampled in 25 government-operated schools within three purposively chosen areas (Kabul, Bamyan, and Mazar-e-Sharif municipalities). We assessed probable psychiatric disorder and social functioning in students with the Strength and Difficulties Questionnaire multi-informant (child, parent, teacher) ratings. We also used the Depression Self-Rating Scale and an Impact of Events Scale. We assessed caregiver mental health with both international and culturally-specific screening instruments (Self-Reported Questionnaire and Afghan Symptom Checklist). We implemented a checklist of traumatic events to examine the exposure to, and nature of, traumatic experiences. We analysed risk factors for mental health and reports of traumatic experiences.Trauma exposure and caregiver mental health were predictive across all child outcomes. Probable psychiatric ratings were associated with female gender (odds ratio [OR] 2.47, 95% CI 1.65-3.68), five or more traumatic events (2.58, 1.36-4.90), caregiver mental health (1.11, 1.08-1.14), and residence areas (0.29, 0.17-0.51 for Bamyan and 0.37, 0.23-0.57 for Mazar-e-Sharif vs Kabul). The same variables predicted symptoms of depression. Two thirds of children reported traumatic experiences. Symptoms of post-traumatic stress were associated with five or more traumatic events (3.07, 1.78-5.30), caregiver mental health (1.06, 1.02-1.09), and child age (1.19, 1.04-1.36). Children's most distressing traumatic experiences included accidents, medical treatment, domestic and community violence, and war-related events.Young Afghans experience violence that is persistent and not confined to acts of war. Our study emphasises the value of school-based initiatives to address child mental health, and the importance of understanding trauma in the context of everyday forms of suffering, violence, and adversity.Wellcome Trust.