A growing body of research shows that social networks and identities have a profound impact on mental and physical health. With such mounting evidence of the importance of social relationships in protecting health, the challenge we face is explaining why this should be the case. What is it that social groups offer that appears to be just as beneficial as a daily dose of vitamin C or regular exercise? This edited book brings together the latest research on how group memberships, and the social identities associated with them, determine people's health and well-being. The volume provides a variety of perspectives from clinical, social, organisational, and applied fields that offer theoretical and empirical insights into these processes and their consequences. The contributions present a rich and novel analysis of core theoretical issues relating to the ways in which social identities, and factors associated with them (such as social support and a sense of community), can bolster individuals' sense of self and contribute to physical and mental health. In this way it is shown how social identities constitute a 'social cure', capable of promoting adjustment, coping, and well-being for individuals dealing with a range of illnesses, injuries, trauma and stressors. In addition, these theories provide a platform for practical strategies that can maintain and enhance well-being, particularly among vulnerable populations. Contributors to the book are at the forefront of these developments and the book's strength derives from its analysis of factors that shape the health and well-being of a broad range of groups. It presents powerful insights which have important implications for health, clinical, social, and organisational psychology and a range of cognate fields.