The subject of this article consists in tracing the outlines and prominent features of the casualization of social action within the framework of structures such as social assistance for children (SAC). These structures are specifically designed to offer stability to fostered minors. The question addressed here is not the cause of this phenomenon—the transformations of the employment market, transformations of the social state, the orientation of social policies or new public management—but rather the effects of precariousness on this assistance activity, a still unexplored angle of research concerning social intervention.