<p>This paper introduces the concept of collective narcissism - an emotional investment in an unrealistic belief about the in-group’s greatness – aiming to explain how feelings about an ingroup shape a tendency to aggress against out-groups. The results of 5 studies indicate that collective, but not individual, narcissism predicts inter-group aggressiveness. Collective narcissism is related to high private and low public collective self esteem and low implicit group esteem. It predicts perceived...