Theoretical and empirical research in public communication of science has a relatively short history compared with the long-standing practice of communicating science to the public. It was only in 1992, for instance, that a dedicated scholarly journal, Public Understanding of Science, was founded. This chapter seeks to contribute to the theoretical understanding of science communication by, first, outlining the key elements of the traditional conception, still implicitly or explicitly widespread within science communication practice and policy, of public communication of science. I then review some of the studies that have challenged different facets of this conception. Finally, I raise the question of which alternative models can best help us understand the contemporary interactions between scientific knowledge and the general public.