In recent public health discourse, the relations between researchers, policy makers, and professionals are often described as ‘gaps’, illustrating the (cultural) differences between these domains. Such descriptions seem to be part of a ‘two communities’-logic: a perception that researchers and policy makers or professionals stem from strictly separated worlds, with distinctive logics, rationales and incentives. In this paper, the author will argue that this prevalent conceptual framework of ‘two communities’, whilst having been extremely helpful in theorizing the difficulties of connecting policy needs with research findings, bears several important limitations when analysing structural collaboratives between researchers and policy makers or professionals. The paper outlines several problematic assumptions and neglected elements that are generally perceivable within this tradition, such as the analytical a priori separation of research, policy and practice domains and the overemphasis on both the heterogeneity between domains and the homogeneity within these domains. Inductively developed insights from the field of science and technology studies (STS) show that the boundaries between research and policy are often much more fluid (and largely rhetorical) than the two communities tradition seems to acknowledge. What needs to be analysed is not only how the boundaries can be bridged, but how – and at what moments – these boundaries are maintained, redrawn or re-established – and for what purposes. This paper focuses on these questions by utilizing the alternative conceptual framework of coproduction. It draws on long term qualitative research to structural collaborations (the Dutch Academic Collaborative Centres for Public Health) to illustrate these points.