Abstract Community participation is widely thought to be important in the improvement of healthcare delivery and in health equity. Yet there is little agreement about what ‘participation’ means in practice, or when it might be necessary. Drawing on the case of healthcare delivery in the UK, we examine key socio‐psychological elements at the heart of community engagement with participatory processes. We explore the link between public participant identities and social representations of patient and public involvement (PPI) among healthcare professionals, and examine the role they play in supporting or undermining inclusive and bottom‐up forms of PPI. The study is ethnographic, using in‐depth interviews with public participants and healthcare professionals involved in PPI, and observation of PPI activities in London. We show that it is crucial to take account of more than individual participants' capacities in order to understand and improve PPI. Professionals' talk about PPI contains contradictory discourses about participant identity. These contradictions are reflected in involvees' self‐understanding and experience as public participants, constraining their subjectivities and forms of knowledge, and crystallizing in their participatory practices. Involvees must negotiate professionals' negative discourses to develop self‐images that reflect their own interests and projects, and that empower them to produce an effect in the public sphere. These processes can hinder successful participation even where there is an institutional infrastructure to promote civic engagement with healthcare. Understanding how involvees construct their own identities through engagement with professional discourses will help develop processes that are positive and enabling rather than negative and limiting. Copyright © 2011 John Wiley & Sons, Ltd.