Although contemporary sociological thought reports a diversification of family forms in society, ‘the family’ continues to influence national and international political agendas. Social workers, as ‘street level bureaucrats’, are social agents that both work with citizens and implement policies made by senior officials. Despite this, the extent to which conceptual and policy developments in family diversity manifest in family-based social work practice remains under explored. This article brings together the findings of two comparative studies, and explores the transfer of conceptual understandings of family, and policy, in England, through two examples: gendered caring expectations and culturally located familial norms. Significantly, we show that, when prompted, social workers recognise family complexity and diversity, but myriad constraints complicate the application of these understandings, and related policies. Bringing together literature from sociology, social policy and social work, this article, thereby, offers a unique lens and highlights a lag between conceptual developments, policy and implementation.