Scholars and police organizations argue that when police officers don a uniform, they imbue a certificate of legitimacy. In our study of 238 police officers, we test the assumption that the police uniform impacts officers’ beliefs about their own legitimacy, and, in turn, their projected behavior when in uniform. We find that, when comparing across various combinations of uniforms and accoutrements, officers in our study tended to prefer their standard uniform as a legitimating device. Moreover, we find that the legitimacy attributed to the standard uniform can impact officers’ willingness to engage in certain behaviors when in uniform, at least for the female officers in our sample. This research supports the important role of officer appearance in shaping police perceptions and behaviors, complementing existing research that examines citizens’ perceptions of police uniforms and accoutrements.