This article examines the visions of citizens' ideal practices regarding technoscientific affairs in a democratic society, namely "imaginaries of model citizens," that underlie three science and public initiatives: public understanding of science, public engagement in science, and citizen science. While imaginaries of citizens are performative and necessary to these initiatives, they are often relegated to the background. I argue that such imaginaries are the result of a complex of perceptions on the nature of science, the role of democracy in scientific activities, and the form of "democratizing" science. The imaginary of model citizens in public understanding of science is of literate citizens who should know science sufficiently, use it in daily life, and support science; in public engagement in science, the model citizen is a responsible one who should engage in the governance of technoscientific issues; and in citizen science, a contributive one who should partake in and enjoy creating scientific knowledge.
Keywords: citizen science; democracy; imaginaries; model citizen; public engagement in science; public understanding of science.