Аннотация:The social environment comprising communities, families, neighbourhoods, work teams, and various other forms of social group is not simply an external feature of the world that provides a context for individual behaviour.Instead these groups impact on the psychology of individuals through their capacity to be internalised as part of a person's social identity.If groups provide individuals with a sense of meaning, purpose, and belonging (i.e. a positive sense of social identity) they tend to have positive psychological consequences.The impact of these identity processes on health and well-being is explored in the contributions to this special issue.In this editorial, we discuss these contributions in light of five central themes that have emerged from research to date.These themes address the relationship between social identity and (a) symptom appraisal and response, (b) health-related norms and behaviour, (c) social support, (d) coping, and (e) clinical outcomes.The special issue as a whole points to the capacity for a social identity approach to enrich academic understanding in these areas and to play a key role in shaping health-related policy and practice.