Research indicates that family structure, family relationships, and family discipline and supervision impact delinquent behaviors. There are three principal ways in which family intervention might help to prevent delinquency: parent education and guidance, preschool education for the children of disadvantaged parents, and support for problem families. Although there are virtually no systematic evaluations of such programs in Great Britain, there is valuable information from experience in the United States. Several studies of parent education, including the Oregon Social Learning Center program, report reductions in the aggressive behavior of young children lasting for up to 1 year. There are as yet no indications of similar effects regarding later delinquency. The only substantial example of a preschool program designed to prevent later delinquency is the Michigan Perry Preschool Project. It focused on children from disadvantaged families. The followup of participants at ages 15 and 19 showed significant improvements compared to the control group in educational achievement, behavior in school, and offending rates. The Yale Child Study Center program provides a wide range of services to disadvantaged families. Follow-up evaluations at age 13 show improvements in school performance (especially behavior) and less risk of involvement in delinquency. 28 references.