Because of increasing dependence on scientific knowledge, citizens, if they are to participate democratically in society, need to be able to take part in decision-making about scientific issues. The ideal of citizenship has always included the concepts of rights and obligations; the notion of scientific citizenship (Irwin 2001) can be perceived as a normative ideal which implies not only that scientific knowledge is important for citizenship in contemporary society but also that citizens can lay a legitimate claim about accountability in scientific research. Citizens interact with science through the mass media, particularly television, which is such a part of the routine of daily life. This interaction is part of their cultural citizenship, the idea of individuals patching together an identity as citizen from all available sources, including mass media, using everyday media texts and culture to understand, take up, reflect on and reform identities that are embedded in communities of different kinds. This thesis examines scientific citizenship by looking at how publics use ‘science on television’ as part of an ethno-epistemic assemblage to inform their everyday actions. Television fits into this assemblage as television viewing practices are embedded in everyday life; this means that local contexts of text–reader interaction are a salient part of ethno-epistemic assemblages. Thematic representations of the assemblages of ‘science on television’ emerged from a production–content–reception analysis of science on Irish television, a framework known as the circuit of mass communication. This research privileges the reception analysis, which was carried out with focus groups of television viewers, because in talking together citizens construct and shape their responses to science on television. The analysis follows how focus group participants, as non-experts, participate in science by talk; speaking is,indeed, their political action, and they use the resources of their particular ethno-epistemic assemblages to construct and contest their paths to knowledge. This is a positive view of the potential of the idea of scientific citizenship. However, this potential is not matched by the television content on offer, which is too often formulaic and uncritical of the institutions of science. I call for an ethos of public journalism which emphasises the relationship between the practice of journalism and the democratic work of citizens in a self-governing republic, and suggest that television journalists and producers are ideally suited to help constitute vital “publics” to deliberate complex issues and engage in collective problem-solving activities. Critical comment on science is a crucial aspect of this public journalism, and television, in conjunction with new media, can become a forum for scientists to hold an interactive dialogue with citizens. Focus group participants are already negotiating their scientific citizenship through talk, and scientists and policy makers need to join these discussions, as science, and its consequences, does not end at the laboratory bench.