Pediatric practice in the next millennium will require greater knowledge of new morbidities, such as acquired immunodeficiency syndrome and social and behavioral disorders, reemergent old disorders, such as tuberculosis, and disorders rarely seen of late in the United States but now being brought here by recent immigrants, such as malaria and other parasitic diseases. Diversity in ethnic and cultural backgrounds and beliefs will continue to increase, and it will need to be understood to prevent and treat diseases of children effectively. Although the current antagonism toward immigrants may lead to a decrease in this particular source of diversity, changes in family structure--such as divorce, gay and lesbian couples as parents, and corporate pressure on families--will continue, requiring pediatricians to understand and to accept this diversity if they are to be the health care providers of children. The increased isolation of individuals from society and separation from families of origin will require pediatricians to be more active in communities and schools and to participate with other disciplines and social support groups. At the same time, the advancement of science and technology will continue to drive what the pediatrician does. Increased survival of children who previously had fatal illnesses will mean more emphasis on care of children who have chronic illnesses. Pediatricians will need to be partners with others in the exciting new fields of risk assessment and prevention of psychosocial disorders.