In this fully revised edition, Marilynn Brewer has added new research and ideas to provide an up-to-date and valuable resource for all those concerned with this key area of social psychology. It is clearer than ever that group identities play a major role in human behaviour, impelling heroic action on behalf of ingroups, as well as horrific atrocities against designated outgroups. Revisions have been made that reflect the relevance of recent international events and the social psychological approaches that can illuminate and explain them. Social psychological understanding of these processes has grown as the study of intergroup relations takes centre stage within the discipline, making this a topical and timely new edition for undergraduate courses in social psychology and the wider social sciences.