The sample of 223 detained offenders in five Colombian cities was divided according to childhood or adolescent onset of antisocial behavior and compared on type of offense, characteristics of family of origin, and personal history. Participating offenders were recruited from police detention centers and only included males between 18 and 30 years of age. A life history questionnaire was employed to collect data on the offenders. Findings revealed no significant differences on type of offense in early and late groups. Individuals with childhood onset of antisocial behavior, however, were more likely than late starters to report multiple problem behaviors at all ages, family antecedents of delinquency and alcohol abuse, greater exposure to family life changes, psychological abuse, severe childhood punishment and lower self-esteem and sense of coherence. These differences were independent of mother's level of education, head of household's occupational level, and family size. The social and cultural context of heterogeneity among offenders related to the age of onset of antisocial behavior is discussed. 21 references, 1 note, and 1 table