Book excerpt: The social psychology of groups forms an integral component of mainstream social psychology courses throughout the western world. It is also of interest to intersecting disciplines such as sociology, organizational and cross-cultural psychology, and language and communication studies. This double volume encyclopedia (the only one in existence) will cover concepts from across the spectrum, from group phenomena to phenomena influenced by group membership, from small group interaction to intergroup relations on a global scale. The proposed Encyclopedia would contain over 400 concepts, written by an international and interdisciplinary gathering of researchers and cover the following topic areas: Methods Theory Cognition Types of Groups Organizations Influence and Persuasion Prejudice and Discrimination Decision Making Conflict and Cooperation Group Structure Group Performance Intergroup Relations in Society Identity and Self