This article investigates how a discourse about the role and value of public participation in science, technology, and innovation emerged and evolved in the research policies of the European Commission. At the beginning of the twenty- first century, two main discourses have been successively institutionalized: the first focused on participation in policy-making, while the second aimed at participation in the production of knowledge and innovation. This paper distinguishes three main institutional phases: (i) a phase dedicated to public participation in the governance of science and technology (2000–2010); (ii) a reframing period of science and tech- nology policies by the Commission to integrate the growing emphasis on innova- tion (2010–2014); (iii) a period focusing on co-creation and citizen science as new ways to involve the public in science and technology (2014-today). Factors such as individual commitments of key policy actors, specific epistemic communities and institutional dynamics within the Commission played a crucial role in shaping the policies of participation. But broader factors are also essential to account for these changes. In this respect, the economic crisis of the late 2000s appears fundamental to understanding how the conception and promotion of public participation in the European science and technology policies have evolved over time. This paper thus offers new insights to the analysis of the political economy of public participation.