A cross-sectional survey of children aged 5–11 years attending 22 primary schools was carried out in Karachi, Pakistan. In the first (screening) phase, broad morbidity rates were measured using the Strengths and Difficulties Questionnaire (SDQ). A total of 968 parents and 793 teachers participated. In the second phase, 100 children were selected for a diagnostic interview using the Kiddie Schedule of Affective Disorders & Schizophrenia for School-Age Children. A weighted rate of 17% (95% CI 6.2–28.3%) was found for common child psychiatric disorders, with a preponderance of behavioural disorders, followed by anxiety and mood disorders. The feasibility study established methods and preliminary rates of child psychiatric disorders, which appear higher than in other countries. School surveys could be an important source of data in low-income countries and form the basis for interventions in the absence of specialist services.