Why does one professional group develop while another stagnates? This article addresses the question on the basis of a study of two social work professions. The first is one of the oldest: the Factory Superintendents Training School (École des surintendantes d’usines) was founded at the end of the First World War. The second, on the other hand, was formally recognised by a diploma of household social economy adviser (conseiller en économie sociale familiale) only in 1973. However, in spite of the reputation of their school, the excellence of their training and even, in certain cases, a legal monopoly, the superintendents largely failed to establish themselves. They currently represent a very small minority of the social services staff of large companies, which is mainly composed of social workers. Family social economy advisers, on the other hand, are one of the most dynamic of the social work professions and the student population is the fastest growing of all. Family advisers have managed to the shift from domestic economy teaching, whereas the superintendents have been confined to family-related issues and have been to some extent excluded from human resources and organisation issues. Among the various hypotheses examined to account for these different paths, the author places particular emphasis on the capacity of professional groups to establish a structure to represent and promote the interests of the profession that is neither narrowly status-oriented nor strictly corporatist, but makes it possible to build alliances.