["Health Expectations, Volume 29, Issue 2, April 2026. ", "\nABSTRACT\n\nBackground\nPatient and public involvement and engagement (PPIE) has many benefits for the design, delivery and dissemination of health research, but this can be difficult to achieve. Systematic reporting and evaluation of PPIE in multi‐year, multisite and complex clinical trials is very limited.\n\n\nMethodology\nThis evaluation presents a multi‐perspective description and evaluation of patient and public involvement within a large‐scale, multisite, longitudinal research programme focused on developing and evaluating a vocational rehabilitation and clinical psychology intervention for individuals recovering from traumatic injury. Conducted as part of the NIHR‐funded ROWTATE research programme (2019–2026), the evaluation explores the scope, impact, and lived experiences of PPIE group members across all phases of the study, from development of the intervention, feasibility study and trial design to intervention delivery, data collection, analysis and dissemination. Employing multiple methods, including open‐ended surveys with PPIE group members and researchers, a ‘You Said, We Did’ activity log, and minute taking, the study identifies key patterns related to PPIE group members' motivations, contributions, personal impact and barriers and facilitators to engagement.\n\n\nResults\nFindings highlight the significant value of PPIE in enhancing study relevance, improving data collection and communication strategies, informing rehabilitation, clinical psychology and health economics components, and shaping intervention delivery. PPIE group members reported a strong sense of purpose and intellectual engagement, despite challenges including communication gaps and role clarity. Researchers valued PPIE contribution to the research, and the positive and enriching experience of working with PPIE group members. Both groups reflected on the barriers and facilitators to PPIE.\n\n\nConclusion\nThe evaluation highlights the importance of inclusive, well‐supported, and transparent PPIE practices and contributes novel insights into the PPIE role in under‐researched domains such as clinical psychology and health economics.\n\n\nPatient or Public Contribution\nTraumatic injury survivors were involved in all processes of this evaluation. This includes research design, funding acquisition, data collection, data analysis and interpretation and the write‐up of this manuscript. Five traumatic injury survivors are co‐authors of this manuscript.\n"]