The program was developed by David Olds and colleagues. It is based on knowledge that the most serious and chronic offenders often display signs of antisocial behavior as early as the preschool years. Three important risk factors associated with the early development of antisocial behavior can be modified. These include adverse maternal health-related behaviors during pregnancy associated with children's neuropsychological deficits, child abuse and neglect, and troubled maternal life course (unintended successive pregnancies, reduced work force participation, welfare dependency, drug abuse, and criminal behavior). A major factor in the program's success that distinguishes this model from other, similar programs is its use of trained, experienced, mature nurses with strong interpersonal skills. Home visits begin during pregnancy and continue for 2 years after the child is born. The home visitors focus simultaneously on the mother's personal health and development, environmental health, and quality of caregiving for the infant or toddler. A full-time nurse home visitor carries a maximum caseload of 25 families. This cost-effective program has been tested over the past 20 years and has the proven ability to reduce the development of antisocial behavior in childhood and later crime and delinquency. Figure, photographs, and 38 references