Research has linked narcissism to a tendency for becoming aggressive based on the perspective that narcissistic people are more prone to ego-threats and more prone to responding defensively to those ego-threats. Also, recent research has been examining the propensity for aggression to escalate as a means to justify prior aggression. This study examined the relationship between narcissism and escalation in aggression and possible mediators of increased aggression. If highly narcissistic individuals are more vulnerable to ego-threats and in turn justify their actions more, then their aggression might escalate more. To examine this, sixty-seven subjects who completed the Narcissistic Personality Inventory prior to the laboratory session were assigned to two groups using a bug-extermination method (though no bugs were actually killed) developed by Martens and his colleagues (in press). They either killed one or five bugs initially and then conducted a subsequent bug-killing task in which they controlled the number of bugs they killed. As predicted, participants who killed five bugs initially killed more bugs during the subsequent bug-extermination task than those who killed only one bug initially. Contrary to predictions, no effects of or interactions of narcissism with the initial bug-killing manipulation emerged. We did find, however, that a subtype of narcissism, that is superiority, affected the self-paced 20 seconds bug-killing behaviour. The limitations, further directions, and implications of this study are discussed.