Changing visions of science and the characterization of scientific expertise have been co-produced with imaginations of ‘the public’ and its proper role in science policy-making. Since the middle of the twentieth century, visions of science as the product of an isolated community devoted to free intellectual inquiry have largely been replaced by the recognition both of scientists’ reliance on public support and of the far-reaching societal consequences of scientific and technological innovation. Consequently, publics have been increasingly brought in to science policy-making and its institutional machinery. Yet simultaneously the practice and theory of public participation in science policy have faced fierce critiques. It has been claimed that the shift towards public dialogue has been merely rhetorical, whilst old visions of the autonomy of scientific progress remain strong and the instrumental imperatives of science policy-making threaten emerging modes of decision-making. This paper explores these developments as an introduction to the new and developing critical public engagement literature, which seeks to constructively engage with these new interactions between scientific expertise, publics and science policy-making. Future pathways for the literature and science policy-making are then suggested.