Public health and medical care interventions have produced dramatic changes in the health of children in the United States. Emerging new morbidities such as behavioral and learning disorders, and child abuse and neglect, highlight the lack of an integrated system of health. Children's developmental vulnerability, dependency, and unique morbidities have been underemphasized in the organization and delivery of health care. The Andersen and Aday model of health care utilization is used to describe financial and nonfinancial barriers to care for children that include family characteristics and organizational characteristics of the health system. Case studies of immunization delivery, children with chronic illness, and mobile populations of children reveal the mismatch between the health care system and children's basic health needs. Integrated service models for high-risk populations of children represent an essential mechanism for coordinating the delivery of medical, developmental, educational, and social services needed by children and families. Universal, coordinated public health and medical services of adequate scope and quality should be assured for children through market and health system reform.