CONTEXT: Epidemiologic studies undertaken in postconflict countries have focused primarily on trauma-related disorders. There is a need to include disabling psychotic disorders in order to plan clinical services in these settings. OBJECTIVES: To estimate the prevalence of key clinical disorders in Timor Leste (East Timor), and to assess cultural factors that may influence help-seeking patterns. DESIGN, SETTING, PARTICIPANTS: A 2-phase total population survey of 1544 adults in an urban and a rural area of Timor Leste. Phase 1 involved a household informant survey using indigenous terms to detect psychosis and a screen of all adults for posttraumatic stress disorder (PTSD) and symptoms of psychologic distress, including depression and anxiety. In phase 2, clinicians interviewed all those identified by household informants and half of those who screened positive in order to assign DSM-IV diagnoses. Disability, explanatory models, and perceived needs were also assessed. MAIN OUTCOME MEASURES: Phase 1: Demographic characteristics; trauma events and PTSD (Harvard Trauma Questionnaire); psychologic distress (Kessler-10 scale). Phase 2: Structured Clinical Interview for relevant DSM-IV diagnoses; the Global Assessment of Functioning Scale and the World Health Organization Disability Assessment Scales; and the modified Short Explanatory Model Interview. RESULTS: The household informant method in phase 1 detected mainly psychotic disorders, and the screen method detected PTSD and depression. Phase 2 yielded a DSM-IV point prevalence estimate of 5.1% (including psychosis, 1.35%; and PTSD, 1.47%). Psychotic disorders were most disabling, primarily attributed to supernatural causes and treated mainly by traditional healers. Those with depression and PTSD experienced substantial disability but had received little treatment. They attributed their mental problems to social and traumatic causes. CONCLUSIONS: Our 2-phase method proved effective for identifying the range of disorders relevant to planning clinical services in postconflict developing countries. The unmet needs of the mentally ill in countries such as Timor Leste pose a major challenge to psychiatry.