In recent years, we have witnessed an explosion of both invited and uninvited forms of public participation in science and technology. Think of consensus conferences on new and emerging technologies like nanotechnologies, "partnership" approaches to the governance of nuclear waste, technology assessments, and public outcries over genetically modified organisms. Whereas it has been argued that public participation in science is losing much of its sway, or that it is a passing fad, recent developments suggest that "participation" in science and technology is continuously being remade and reinvented. These developments include the rapid emergence of citizen science, garage science, living labs, and art-science forms, among many others. In light of these developments, this Topical Day asks how public participation in science and technology is transformed in the face of new challenges, opportunities, and events. Speakers from a wide range of sociotechnical fields and contexts will provide their views on this question by drawing lessons from past experiences and by reflecting on the present and future of public participation in science and technology.