There is a general consensus as to the importance of involving the family in the rehabilitation treatment of adolescent substance abuse; but there is little documentation as concerns the nature of family influence in this matter. The objective of the present study is to come to a better understanding of how family involvement contributes to the rehabilitation process. The method consists of semi-standardized individual interviews carried out with two youngsters undergoing substance abuse treatment, and with the parents and clinicians monitoring their progress. We have also collected complementary pre- and post-treatment data regarding the seriousness of family difficulties and substance abuse experienced by these two young people. Results. The narratives of these various stakeholders underline the benefits of a constant parental involvement at each stage of the rehabilitation treatment.