Research into social networks has been advancing over several decades, originally in relation to the general population and more recently in relation to their duences on health and mental health. The recent full implementation of the Community Care Act, with its stress on the role of carers and networks, reinforces the need for mental health nurses to be aware of these issues. This selective review examines some of the ways in which social networks can be analysed, explores the relationship between social networks and social support, and considers the effects of social networks and social support on mental health. Research into the social networks of people with long-term mental ill-health is discussed, and implications for mental health nursing in all care settings are addressed.