Social identity theory proposes that much of our identity, attitudes, beliefs, and even our behaviors are grounded in groups that we affiliate with, or groups that are important to us. The groups (eg: class, sports team, religion, family) which we belong to are an important source of pride, self-esteem, and identity. Additionally, the groups that we are a part of give us a sense of social identity - a sense of belonging to the social world. This book provides and discusses new developments in social identity research.