Cross-national differences in questionnaires do not necessarily reflect comparable differences in disorder prevalence.

Purpose: To examine whether the widely used Strengths and Difficulties Questionnaire (SDQ) can validly be used to compare the prevalence of child mental health problems cross nationally.

Methods: We used data on 29,225 5- to 16-year olds in eight population-based studies from seven countries: Bangladesh, Brazil, Britain, India, Norway, Russia and Yemen. Parents completed the SDQ in all eight studies, teachers in seven studies and youth in five studies.