After approximately 4 weeks of basic military training, the recruits completed a questionnaire that contained about 900 items, which included details of the sociodemographic circumstances of their childhood and adolescence, including delinquency, mental health issues, and deviant behavior. A total of 1,510 recruits had lived continuously with their mothers, but not necessarily all the time with their fathers, before age 12; 140 recruits had lived continuously with their father, but not necessarily all the time with their mother, before age 12; 752 recruits had lived with a foster family or with relatives for more than 1 year before age 12; and 171 recruits had lived in an institution, most often children's homes but also mainstream hospitals or orphanages, for at least 1 year before age 12. The study found that recruits who had experienced some form of family disruption prior to age 12 were more likely to have engaged in delinquent behavior; however, intact but high-conflict families predicted the same prevalence of delinquency as disrupted families. Boys who did not live with their mothers, especially when they had lived in an institution before age 12, were most likely to become persistent offenders. The study thus identified a number of subgroups within the broad classifications of disrupted and intact families that were linked to the rate and severity of delinquency. Within these subgroups, it is important for future research to identify the particular risk and protective factors related to negative and positive outcomes. 4 tables and 21 references