This qualitative study draws on and extends two§important concepts of the public understanding of§science literature: scientists understandings of the public , and the currently popular notion of§science-public dialogue. Using data from interviews§with scientists and engineers, the 'understanding of§the public by scientists is examined. Constructions§of publics are also an emphasis in a detailed case§study of informal science-public dialogue at the Dana§Centre, London. Here structures of power and§authority are more traditional than the dialogue§movement s rhetoric would suggest, but there is also§continual resistance to and contestation of these§structures. To conclude, the threads of analysis are§drawn together to provide a theoretical reasoning of,§and model for, informal dialogue processes which are§able to utilise the sociological complexity of§scientists talk.