["Health Expectations, Volume 29, Issue 4, August 2026. ", "\nABSTRACT\n\nBackground\nPatient and public involvement (PPI) is increasingly promoted in health services research, yet empirical evidence remains limited on how participatory governance is operationalised in research practices.\n\n\nMethods\nThis qualitative study explored patient partners' experiences of involvement in the PaRole OncO France (PROOF) research project, a multicentre participatory action research (PAR) project aimed at adapting, implementing and evaluating a peer support intervention in oncology. Semi‐structured interviews were conducted with patient partners involved in project governance. Data were analysed using inductive thematic analysis, with patient partners involved in validating analytic outputs.\n\n\nResults\nSeven of the eight invited patient partners (PPs) were interviewed. Three interrelated themes emerged: (1) personal invitation as recognition: a catalyst of engagement, whereby being personally solicited was experienced as recognition of experiential legitimacy; (2) securing a ‘real place’: relational trust, dedicated spaces and institutional frictions, capturing both the conditions enabling genuine co‐governance (dedicated spaces, recognition of experiential knowledge and responsive research teams) and the administrative and temporal constraints that strained it; and (3) reciprocal transformation: perceived impacts on the research and on personal trajectories. Patient partners perceived meaningful contributions to intervention design and team cohesion, alongside personal benefits such as skills development and network building. Persistent barriers were primarily structural, including administrative constraints, research temporalities and regulatory procedures.\n\n\nConclusion\nPROOF illustrates how intentional participatory governance mechanisms can support sustained PPI in research. Addressing administrative barriers, clarifying roles and nurturing trust and communication are crucial for meaningful participation in oncology research.\n\n\nPatient or Public Contribution\nThe qualitative data presented in this manuscript were obtained through interviews with patient partners. Patient partners co‐designed governance structures, participated in all committees, co‐facilitated co‐construction workshops, and contributed to data interpretation and manuscript validation.\n"]