Poverty, marginalization, vulnerability... The lexical changes made in order to capture issues in social cohesion are not trivial. They reflect social representations and understandings of integration of and into society. In this article different questions are raised regarding the evolution of these concepts in relation to a new theoretical avenue: “vulnerability”, the inputs of which are put forward. Moreover, these conceptual changes are to be linked to the evolution of social work. If concepts change, practices do so as well. How does the way we define concepts and elaborate intervention practices regarding populations with social insertion issues evolve? What impact do these transformations have on social work?