There is an apparent consensus among mental health stakeholders regarding the implementation of a preventative approach to disorders of early parental relations. Nonetheless, numerous forms of resistance appear when practical steps towards such an approach are taken. Such resistance reflects both different conceptions of mental health, institutional inertia and coordination problems. The example of attempts to formalise and entrench a network of actors involved in early psychical prevention in the Northern boroughs of Marseille illustrates both the attractiveness of such a preventative objective and the obstacles it encounters. However, it is of great importance for the actors involved that a true strategy be developed to express difficulties in family relations: only thus can the preventative ideal to which infant-care and mental-health professionals subscribe take practical form and provide proper support for fragile parenting in the perinatal period. From this perspective, a threefold scheme appears necessary: training of case workers, formalisation of networking, and active participation by parents in prevention.