This article uses data from two U.K. studies in order to explore the meanings attached to public engagement. It focuses on two issues of importance to contemporary discussions of science communication: the degree to which there has been a smooth transition, in practice, from models of public understanding of science to those of public engagement with science and technology (PEST), and the histories, or genealogies, of such models. Data from two qualitative studies-a case study of one of the United Kingdom'ssix Beacons for Public Engagement and a study of contract research staff-are used to characterize the ways in which U.K. academic communities understand PEST. It is argued that engagement is construed as multiple, relational, and outcomes oriented, with seven key outcomes ranging from better research to empowered individuals. These differences are traced to personal and professional backgrounds, suggesting that multiple and overlapping meanings around PEST are derived from particular histories that have been brought together, through the rubric of public engagement, in assemblages such as the Beacons.