Background Patient and public involvement means researchers working with members of the public, patients or carers to jointly plan and carry out research. Aim This article is written by members of three involvement groups, and the university employees that they work with. We wanted to jointly reflect on what enables our collaborative work, and what the challenges are for everyone involved. What we did and how we did it We wanted to establish what the literature defines as 'good' public involvement and compare this with processes and practices in our involvement groups. We therefore carried out a literature review and each group met separately to discuss what characterises good involvement, and what the challenges are. From these discussions we developed a set of descriptions about each group. We compared the literature review findings with what came out of the discussions within the involvement groups. Findings Some of the involvement principles from the literature were similar to the priorities of the involvement groups. In addition, the groups identified characteristics of 'good' involvement practice that were not reported in the literature: passion and enthusiasm, informal and welcoming meeting spaces, and opportunities to share lived experiences. In this article we present examples of how principles for good involvement are practiced in these groups, and difficulties we have experienced.

Introduction: Patient and public involvement in research is anchored in moral and epistemological rationales. Moral rationales relate to the public having a right to influence how knowledge about them is generated. Epistemological rationales relate to how research design and implementation can improve when informed by experiential, as well as technical, knowledge. In other words, public involvement can increase the epistemological resources of researchers, and contribute to research that is fit for purpose and has high external validity. Methods: This article presents an analysis of 3 meetings and 11 interviews with public collaborators and researchers in three UK-based health research studies. Data comprised transcripts of audio-recorded research meetings and interviews with public collaborators and researchers. Data were first analysed to develop a datainformed definition of experiential knowledge, then thematically to investigate how this experiential knowledge was considered and received within the research space.Results: At meetings, public collaborators shared their experiential knowledge as stories, comments, questions, answers and when referring to their own roles. They were aware of crossing a boundary from everyday life, and some adapted their contributions to fit within the research space. Although researchers and public collaborators made efforts to create an inclusive climate, obstacles to impact were identified.Conclusions: Considering experiential knowledge as a boundary object highlights that this knowledge has a different form to other kinds of knowledge that contribute to research. To enable impact from experiential knowledge, researchers need to create a space where public collaborators experience epistemic justice.