Children's healthy mental development has never been the focus of long-term, committed public health policy in the way that early physical health and development have been. We discuss four types of societal response to illness-cure, care, control, and prevention--and trace the history of public health in terms of its special responsibility to control and prevent disease. We identify four periods in the history of public health: the Sanitarian era (up to 1850), the Bacterial era (1850-1950), the Behavioral era (1950-present), and the Communitarian era (the next century). Looking at this history from the viewpoint of the developmental psychopathology of the first 2 decades of life, we trace progress in public health responses to children with mental illness, from a philosophy of control by isolation toward one of preventive intervention. We examine primary, or universal, prevention strategies that have been tried, and we suggest some that might be worth reconsidering.