This thesis provides a sociological analysis of the process of the construction of meanings of Patient Public Involvement (PPI) policies within two Local Involvement Networks (LINks) and two Community Health Councils (CHCs), which were citizen-engagement organisations that formed part of the health care systems of England and Wales. Drawing on symbolic interactionism, the study uses the selected bodies as sites to explore comparatively how frontline actors (such as volunteers, salaried staff and NHS professionals) understood and enacted PPI in everyday work. An ethnographic approach was employed to investigate the interaction and the meaning-making activities of stakeholders in local PPI arenas. The research is based on a combination of observations, semi-structured interviews and documentary analysis undertaken over a period of sixteen months. The study shows that the meanings of PPI in LINks and CHCs is shaped by social processes, such as the interplay between informants' understandings of role and everyday relationships between volunteers, officers and NHS professionals in the course of the work. The research suggests that, despite different legislation, Welsh and English informants understood their place in CHCs and LINks in similar ways by drawing on established working practices and a notion of the ideal volunteer. Volunteers made sense of their role by drawing on images of 'the public', viewed as an imagined community of people with negative attributes against which volunteers constructed the positive meaning of their own role. Informants in the study understood PPI in multiple ways that evidenced the relevance of the organisational and social context in 'doing involvement'. In discussing how local stakeholders' concerns to comply with the legal requirement 'to do PPI' were translated into practical devices to show evidence that involvement was proceeding, the concept of juridification is used to develop a better understanding of grassroots actors' interpretations of policy