A lot of work has looked at Patient and Public Involvement (PPI) in research, but there has been less looking at PPI in service delivery. In both areas, we know little about what PPI works, for whom, why, and where. There are also limited definitions of PPI and what it actually is. Few studies have looked at PPI reference groups and the experiences of the advisors who contribute to the groups. This study will look at some of those research gaps; it is part of the Collaborations for Leadership in Applied Health Research and Care West Midlands (CLAHRC WM) Implementation Science and Organisation Studies (ISOS) theme of work, based at Warwick Business School. The ISOS work theme looks at ‘implementation’ - identifying how, where and why research findings can be turned into services for patients, which use the evidence-base of what works. So the proposed study will look at what PPI is in CLAHRC WM, and how it contributes to the work of the CLAHRC, including implementation.