This article describes a longitudinal analysis of the behavior of a birth cohort of 435 boys. 4 groups were defined at age 13 on the basis of both self-reported delinquent behavior and professional diagnosis of Attention Deficit Disorder: ADD + delinquent, ADD only, delinquent only, and nondisordered. Biennial correlates of delinquency (antisocial behavior problems, verbal intelligence, reading difficulty, and family adversity) were traced across childhood. The ADD + delinquent boys consistently fared the worst on the assessments of family adversity, verbal intelligence, and reading. Their antisocial behavior began before school age, escalated at school entry, and persisted into adolescence. The ADD-only boys had normal family, intelligence, and reading scores, and showed only mild antisocial behavior in middle childhood. The delinquent-only boys showed no early risk from family, low intelligence, or reading deficit, and remained relatively free of conduct problems until they initiated delinquency at age 13. Persistence of criminal offending beyond adolescence is predicted for the ADD + delinquent boys.