Public communication initiatives play a part in placing complicated scientific claims in citizen-consumers’ everyday contexts. Lay reactions to scientific claims framed in public communication, and attempts to engage citizens, have been important subjects of discussion in the literatures of public understanding and public engagement with science. Many of the public communication initiatives, however, address lay people as consumers rather than citizens. This creates specific challenges for understanding public engagement with science and scientific citizenship. The article compares five different understandings of the relations between citizen-consumers and public issue communication involving science, where the first four types are widely represented in the Public Understanding of Science discussions. The fifth understanding is a practice theoretical perspective. The article suggests how the public understanding of and engagement in science literature can benefit from including a practice theoretical approach to research about mundane science use and public engagement.