The health development organization (HDO) is a new approach to the organization and delivery of children’s health and social services. The HDO would combine the best features of vertically integrated HMOs with horizontally integrated, child‐focused social services and longitudinally integrated health promotion strategies. Its mandate would be to develop the health of children in a community. The impetus for creating HDOs is a growing body of evidence in chronic disease epidemiology, developmental psychopathology, early intervention research, and life course cohort studies that point to childhood as the period of life during which adult health status is determined and the opportunities for health capital formation are highest. Thus, a new kind of health care organization or framework, like the HDO, is needed to integrate a full range of critical services for promoting children’s development.