The deficiencies of technocratic approaches to governing emergent risks and technologies in the face of radical uncertainty, political controversy and public distrust, has brought about increasing calls, and in some quarters concerted action, to democratise science across western democracies. This paper discusses some recent Uk examples of participation in contested science and technology decision-making, focusing on a number of high profile cases which are helping policy-political, business and civil society actors gain a better understanding of what precisely may be gained from bringing a much wider range of knowledges and values into the process. The Uk experience suggests that pressures are growing for more upstream (i.e. very early) engagement in opening up contentious issues to much wider societal framings than hitherto. The paper explores the contributions being made by an emerging epistemic community of academics and practitioners in the design, implementation and evaluation of participatory processes that are fit-for-purpose.