In the past five years, informal science institutions (ISIs), science communication, advocacy and citizen action groups, funding organizations, and policy-makers in the UK and the USA have become increasingly involved in efforts to promote increased public engagement with science and technology (PEST). Such engagement is described as taking place within the context of a “new mood for dialogue” between scientific and technical experts and the public. Mechanisms to increase PEST have taken a number of forms. One of the most visible features of this shift towards PEST in ISIs is the organization and staging of adult-focused, face-to-face forums that bring scientific and technical experts, social scientists, and policy-makers into discussion with members of the public about contemporary scientific and socioscientific issues related to the development and application of science and technology. A significant aspect of the literature on efforts to increase PEST has focused on the development of a unifying evaluative framework for determining what counts as success for PEST mechanisms, and how success (or lack thereof) can be empirically measured. In this article, we draw from our experiences as UK-based and US-based “dialogue event” practitioners and researchers/evaluators to suggest that these existing evaluative criteria are insufficient to explore the role and value of ISI-based “dialogue events.” Instead, we suggest that it may be productive to research and evaluate these ISI-based “dialogue events” as sites of learning. Secondly, however, we show through a discussion of our own research frameworks that understanding these “dialogue events” as sites of learning does not intuitively provide a framework for understanding what counts as success for these efforts. Instead, research on the role of “dialogue” within the educational literature—and the connections between “dialogue” and competing understandings of the nature of science and society—offers a multiplicity of approaches to defining the terms and goals of these events. Finally, we identify two broader implications of researching and evaluating these “dialogue events” as sites of learning for ISIs and all efforts to increase PEST.