(Received 10 November 2008; accepted 13 December 2008)

This paper examines the psychology of ethnic, national, religious or political ideological groups composed of thousands or millions of people. In such large groups most of the individuals will never meet during their lifetimes. But, they share a persistent sense of sameness, “large-group identity.” This paper examines how this abstract concept, large-group identity, can become the central force that influences international relationships. Psychoanalysts who are willing to become involved in interdisciplinary initiatives can provide information to the diplomats about large-group psychology in its own right and suggest peaceful strategies for international conflicts.