For youth, the labour market is a site for the construction of margins. The dissociation of the economic and social aspects of work is at the heart of a process leading a growing number of them to the limits of exclusion. With the acceleration of change, established regulating mechanisms are no longer able to attenuate certain negative effects on individuals. Insertion and exclusion approaches currently polarize youths in their individual strategies vis-a-vis certain work characteristics: precariousness, flexibility, intermittence, selectiveness and competition. Collective strategies are inadequate and need to be reinvented.