This chapter has been written from the stance of a patient and public contributor to mental health research. It examines the role of patient and public involvement in mental health research which has evolved since the mid 1960s and continues to do so. Examining the people, roles and research and providing a definition for the different stages of Patient and Public Involvement, the chapter looks at how these roles interact, the ethics and rationale for involvement, the power relations between the various parties, whether involvement is moving the research agenda closer to preventative health care, and the subject of equality, diversity and inclusion. The difficulties of working with people with serious mental health issues are addressed. Case studies are given to illustrate various points. Subjects such as training and language are included. The complex subject of evaluation and impact and how they can be resolved are raised. Finally, the chapter concludes by inviting the reader to consider what ‘good PPI’ is, and how it is done.