Strong evidence links early problem behavior to later adolescent delinquency and serious adult criminality. Factors involved in early problem behavior are the absence of adequate economic and social resources, criminality of parents, and the lack of good parenting skills. Research documents the effectiveness of early prevention and intervention in changing the behaviors of children exposed to such conditions in their early years. Effective early childhood programs attempt to ameliorate more than one or two factors associated with delinquency and focus on multiple problem behaviors; they are designed for children of specific ages and at specific stages of development; and they involve long-term efforts that often last several years. The U.S. Department of Justice should take a leading role in the interagency development of early prevention efforts that are promising. These include home visitation programs for mothers at risk of abusing and neglecting their children, educational daycare programs with a home visitation component, and the provision of all services necessary for the safety and healthy development of children. Further, early prevention and intervention efforts should target parents who are under the supervision of the criminal and juvenile justice systems and the family courts. This should include prenatal counseling, perinatal care, therapeutic communities, parenting programs, and the recruitment of more stable, extended family members to care for the children of offenders. For older, more persistent juvenile offenders, community-based programs should focus on behavioral skills. Finally, the Department of Justice should design and support high-quality evaluations of major prevention and intervention programs.