This article reports a comparison on outcomes of 26-year-old males who were defined several years ago in the Dunedin longitudinal study as exhibiting childhood-onset versus adolescent-onset antisocial behavior and who were indistinguishable on delinquent offending in adolescence. Previous studies of these groups in childhood and adolescence showed that childhood-onset delinquents had inadequate parenting, neurocognitive problems, undercontrolled temperament, severe hyperactivity, psychopathic personality traits, and violent behavior. Adolescent-onset delinquents were not distinguished by these features. Here followed to age 26 years, the childhood-onset delinquents were the most elevated on psychopathic personality traits, mental-health problems, substance dependence, numbers of children, financial problems, work problems, and drug-related and violent crime, including violence against women and children. The adolescent-onset delinquents at 26 years were less extreme but elevated on impulsive personality traits, mental-health problems, substance dependence, financial problems, and property offenses. A third group of men who had been aggressive as children but not very delinquent as adolescents emerged as low-level chronic offenders who were anxious, depressed, socially isolated, and had financial and work problems. These findings support the theory of life-course-persistent and adolescence-limited antisocial behavior but also extend it. Findings recommend intervention with all aggressive children and with all delinquent adolescents, to prevent a variety of maladjustments in adult life.