In this contribution we review a family of social psychological theories, most notably Social Identity Theory (SIT) and Self-Categorization Theory (SCT), which together constitute what we refer to as the Social Identity Approach. These theories are linked by their concern with the processes which surround the way that people define themselves as members of a social group – which, here, is the meaning of the term ‘social identity’. At a conceptual level, this approach serves to transform the understanding of identity in psychology. It stresses the sociality of the construct in at least three ways. First, social identity is a relational term, defining who we are as a function of our similarities and differences with others. Second, social identity is shared with others and provides a basis for shared social action. Third, the meanings associated with any social identity are products of our collective history and present. Social identity is therefore something that links us to the social world. It provides the pivot between the individual and society.
But the social identity approach should not be seen as an exercise in social theory. Within its broad framework, social identity researchers have specified detailed processes that give practical insights into the ways that groups work in society. We will address a number of these including the nature of influence and persuasion, how leadership works and the nature of group stereotypes. This work has been applied to the behaviour of many different types of groups from electorates, to crowds, to work organizations. Indeed the power of the theory is in direct relationship to its range of application.