This paper draws on the findings of a study within the ESRC's Democracy and Participation Programme. It explores the processes of participation within deliberative forums-such as user panels, youth forums, area based committees - developed as a means of encouraging a more active, participating mode of citizenship and of improving welfare services by making them more responsive to users. Our findings open up a number of issues about constraints on the development of 'collaborative governance'. To understand these constraints, we suggest, there is need to locate participation initiatives in the context of government policy, to explore ways in which such policy is interpreted and enacted by strategic actors in local organisations and to examine the perceptions of members of deliberative forums themselves. Our findings highlight the constraints on the 'political opportunity structures' created by the enhanced policy focus on public participation, and the consequent limits to 'collaborative governance'. We discuss how governance theory and social movement theory can each contribute to the analysis, but also suggest productive points of engagement through which each of these bodies of theory might enrich the other.