Objective: This study aimed to identify the pathways through which a preventive intervention targeting young low-SES disruptive boys could result in lower crime involvement during adulthood. Method: The preventive intervention was implemented when the children were between 7 and 9 years and included three components (i.e. social skills, parental practices, teacher support). Participants (N = 250) were randomly allocated to the intervention or to a control group. The tested pathways included antisocial behaviour, school engagement, parental supervision and friends' deviancy, both during early and middle adolescence. Crime involvement was assessed in early adulthood. Results: The intervention reduced adult criminal involvement via reduced early and middle adolescent antisocial behaviours. Conclusion: This study adds to the small group of studies that have examined the mechanisms through which early preventive interventions might impact distal outcomes.