Presented as a panacea for the problems of environmental management, ‘participation’ conceals competing frames of meaning. ‘Ladders of participation’ explain insufficiently why public engagement is often limited to consultation, even within so-called higher level partnerships. To explain how participation is shaped to produce more or less symmetric exchanges in processes of deliberation, this article distinguishes between (1) discourses/practices, (2) frames and (3) power effects. This article’s empirical focus is the experience of participatory catchment organisations and their central but under-researched role in integrated catchment management. In addition to an analysis of policy statements and other relevant documents, this article draws on qualitative interview and participant-observation data gathered in an international participatory knowledge exchange that we facilitated among four participatory catchment organisations (and various other agencies). Results suggest that while statements about legislation promise symmetric engagements, the mechanics of legislation frame participation as asymmetric consultation. In their own arenas, participatory catchment organisations deploy participation within a framework of grassroots democracy, but when they engage in partnership with government, participation is reshaped by at least four competing frames: (1) representative democracy, which admits, yet captures, the public’s voice; (2) professionalisation, which can exclude framings that facilitate more symmetric engagement; (3) statutory requirements, which hybridise participatory catchment organisations to deliver government agendas and (4) evidence-based decision-making, which tends to maintain knowledge hierarchies. Nevertheless, participatory catchment organisations proved capable of reflecting on their capture. We thus conclude that the co-production of science and society, and the power effects of framing, must become explicit topics of discussion in processes of environmental policy deliberation for participation to result in more symmetric forms of public engagement.