The involvement of parents within child and family social work has become an important research topic during the past few decades. Within this research, a lot of attention is paid to partnership, which is recognised as a dominant concept in current thinking about the parent-worker relationship in present-day practice. The debate on parent-worker relationships, however, seems to be mainly focussed on the individual relationship between the parent and the social worker. Based on a historical analysis of policy documents on a Belgian child and family welfare service, this article offers a historical and sociopolitical contextualisation of the current debate on the parent-worker relationship. The analysis reveals that sociopolitical ideas about the responsibilities of the state, the community and the private family have induced a continuous reflection on which children and parents should be seen as the most appropriate clients for a particular service, as well as an ongoing development of diagnostic instruments to legitimise inclusion and exclusion of families within child and family social work. Consequences for parent-worker relationships in child and family social work are discussed, as well as some implications for future research on child and family social work practices.