Résumé : The article analyses the emergence of a new and sharply becoming visible category of the delinquent population within the child protection system in the French community in Belgium : young people prosecuted for « sexual assault on a young person ». At the heart of these processes and very much part of the « problem » posed to professionals working in this area, politicians and academics are the different ways disciplines regard the issues. The method used is based on a conceptual framework of Christian Debuyst, which attempts to look again at theoretical propositions by contrasting them with qualitative data collected through group analysis by people from different professions.