We reviewed randomized trials of prenatal and infancy home-visitation programs for socially disadvantaged women and children. Some home-visitation programs were effective in improving women's health-related behaviors during pregnancy, the birth weight and length of gestation of babies born to smokers and young adolescents, parents' interaction with their children, and children's developmental status; reducing the incidence of child abuse and neglect, childhood behavioral problems, emergency department visits and hospitalizations for injury, and unintended subsequent pregnancies; and increasing mothers' participation in the work force. The more effective programs employed nurses who began visiting during pregnancy, who visited frequently and long enough to establish a therapeutic alliance with families, and who addressed the systems of behavioral and psychosocial factors that influence maternal and child outcomes. They also targeted families at greater risk for health problems by virtue of the parents' poverty and lack of personal and social resources.