Research has found that narcissists behave aggressively when they receive a blow to their ego. The current studies examined whether narcissistic aggression could be reduced by inducing a unit relation between the target of aggression and the aggressor. Experimental participants were told that they shared either a birthday (Study 1) or a fingerprint type (Study 2) with a partner. Control participants were not given any information indicating similarity to their partner. Before aggression was measured, the partners criticized essays written by the participants. Aggression was measured by allowing participants to give their partner loud blasts of noise through a pair of headphones. In the control groups, narcissists were especially aggressive toward their partner. However, narcissistic aggression was completely attenuated, even under ego threat, when participants believed they shared a key similarity with their partner. Copyright © 2006 Association for Psychological Science.