A program of prenatal and infancy home visitation by nurses was tested as a method of preventing a wide range of health and developmental problems in children born to primiparas who were either teenagers, unmarried, or of low socioeconomic status. Among the women at highest risk for care-giving dysfunction, those who were visited by a nurse had fewer instances of verified child abuse and neglect during the first 2 years of their children's lives (P = .07); they were observed in their homes to restrict and punish their children less frequently, and they provided more appropriate play materials; their babies were seen in the emergency room less frequently during the first year of life. During the second year of life, the babies of all nurse-visited women, regardless of the families' risk status, were seen in the emergency room fewer times, and they were seen by physicians less frequently for accidents and poisonings than comparison group babies (P less than or equal to .05 for all findings, except where indicated.) Treatment differences for child abuse and neglect and emergency room visits were more significant among women who had a lower sense of control over their lives.