This work explains how from a clinical observation the process of adolescence concerns the whole family and obliges the different partners to carry out a specific work whose stakes are certainly different depending on whether they are considered from the parent’s or from the adolescent’s perspective. Two notions help to understand those stakes. On the one hand, the process of separation-individuation and, on the other hand, the attachment with its tribulations. The therapy, focussed on these elements, helps the adolescent to subjectivate himself by taking into account that which is a matter for a transmission between the generations. In these conditions, family therapy often constitutes a preliminary step towards an individual work more centred on the adolescent’s internal world.