In 1957, the British-Indian child psychiatrist Dr Elwyn James Anthony travelled to the Zurich International Congress of Psychiatry to show a film featuring 70 children with such complex symptomatology and behaviour that they betrayed the certainty of contemporary theories of developmental psychology and psychoanalysis. This article examines the significance of Anthony's film to the creation of new scientific models in international developmental psychology and psychiatric epidemiology. It marked a significant change in the use of filmed evidence that sought to create a truly global and universalist approach to atypical child development based purely on scientific observations. This new observational work was important in shaping new internationally ratified models to study the epidemiology of children's psychiatric conditions.