This study on adolescent offenders and adolescents not involved in delinquent activities led to the following results : delinquency develops in three stages : emergence, activation, aggravation, and regresses between two phases (emergence-activation ; activation-aggravation). These phases appear respectively at the latency age, pre-adolescence, mid-adolescence, and in late adolescence. Three types of family dysfunctions (primary, secondary, and tertiary) contribute to the development of delinquency. Positive transformation of these dysfunctions leads to delinquency regression. Our results provide a study model different from the hierarchical Quebecker model.