A current trend in sociology characterises the end of the twentieth century as obsessed with risk. Ulrich Beck and Anthony Giddens are perhaps the leading expositors of this theme. Both emphasise a break with the past as the last millennium approached its conclusion, whereby changes in patterns of work, technological developments and the demise of traditional social forms have ushered in a new modernity. In their view, social organisations became more reflexive in their assessments of the circumstances of daily life, at a time when new technologies created the possibility of damage on a global scale. The result in the new social world is a society focused on risk. Some aspects of this assessment are uncontroversial. New technologies have emerged, whilst the role of the nation state has changed since its apogee in the nineteenth century. Other aspects of this new vision are, however, empirically more problematic. Furthermore, the degree to which social changes actually had the effects identified by Beck and Giddens remains an open question. Using the early twentieth-century regulation of mental defectives as a case study, this paper will interrogate this ‘discontinuist’ vision, exploring whether and how our understanding of risk has changed.