Jurgen Grotz, PhD, is the Director of the Institute for Volunteering Research (IVR) at the University of East Anglia, UK. He has co-edited the Palgrave Handbook of Volunteering, Civic Participation, and Nonprofit Associations (2016).Mary Ledgard is a retired researcher who has served as a trustee of Healthwatch Norfolk, UK, and is currently a PPI representative in the fields of health and social care.Fiona Poland is Professor of Social Research Methodology at the University of East Anglia, UK and has worked for many years to promote inclusive community research. She is journal editor of Quality in Ageing and Older Adults.

• 1. Introduction.- 2. Historical and Conceptual Background of Public Involvement.- 3. PPI in Research Practice.- 4. PPI in Research Ethics and Ethics in PPI.- 5. Critical Perspectives on Patient and Public Involvement in Research.- 6. The Coherence Model.- 7. Conclusion.