From early twentieth century social reform movements emerged the ingredients for both child and family psychiatry. Both psychiatries that involve children, parents, and families began in child guidance clinics. Post–World War II intellectual creativity provided the epistemological framework for treating families. Eleven founders (1950–1969) led the development of family psychiatry. Child and family psychiatrists disagreed over the issues of individual and family group dynamics. Over the past 25 years the emerging sciences of interaction, in the context of the Primate Social Organ System (PSOS), have produced the evidence for the family being the entity of treatment in psychiatry.