Recent work has demonstrated that there are important continuities in theories of social pathology, ranging from the ‘residuum’ of the 1890s to the ‘underclass’ of the 1990s. Yet, while concepts about the ‘underclass’ have been marked by important continuities over time, there have also been important changes. This article looks at the ‘problem family’ of the 1950s and uses evolving attitudes as a means of exploring the social history of social work in Britain between roughly 1940 and 1970. In particular, it attempts to look at the issue through the eyes of four different interest groups whose members and ideas overlapped but which can none the less be considered as having separate identities. These comprise: the Eugenics Society and other individuals interested in eugenics, new voluntary organizations such as Pacifist Service Units, medical personnel including Medical Officers of Health, and a broad coalition of academics and practitioners in the emerging social work profession. The article concludes that the issue of the ‘problem family’ provides revealing insights into the ways in which the attitude of the emerging social work profession diverged from, but none the less had close links with, the approach of other professional interest groups.