In the modern world, alien rulers are generally perceived to lack legitimacy. Political legitimacy is important because it is thought to be the principal alternative to coercive institutions. Little empirical evidence supports these claims, however. We devise a laboratory experiment that isolates alienness from other ruler characteristics. The experiment tests whether alien rulers have less legitimacy than native rulers, and whether the ability to punish compensates for this disadvantage. Using American and Israeli college student samples, we find that alien rulers receive less compliance than native rulers, and that the ability to punish does not allow alien rulers to "catch-up" with native rulers.