This chapter describes the events that led to the development of pediatric intensive care. The origins of pediatric intensive care are linked to pediatric surgery, respiratory medicine, and pediatric anesthesiology. The formulation of these specializations grew in tandem with the pediatric intensive care unit (PICU). It describes the evolution of characteristics of the levels of care. The role of subspecialty units is also addressed. By addressing the history and components of PICUs it is easier to understand programmatic needs. Since the 1960s, the intention of pediatric critical care medicine, a subspecialty of intensive care and pediatric care medicine has been the "surveillance and support of vital system functions in critically ill or injured infants, children, and adolescents, and their eventual restoration to health". The need for specialized units for intensive care has been clearly articulated by the Committee on Hospital Care of the American Academy of Pediatrics (CHCAAP) and Pediatric Section of the Society of Critical Care Medicine.