Although there is a substantial body of work examining attitudes towards the police, no measure has been developed to consistently capture citizens’ beliefs regarding police legitimacy. Given that police conduct has garnered a great deal of attention, particularly in the last few years, the current research sought to develop a scale measuring perceptions of police legitimacy. Across multiple studies, items were created and the scale’s factor structure explored (Study 1 and Study 2), the factor structure was confirmed (Study 3a), and the predictive validity of the scale was tested (Studies 3b–3d). Results provided evidence for a reliable and valid 34-item scale with a single-factor solution that predicted multiple outcomes, including justification of a police shooting (Study 3b) and resource allocation to a police charity (Study 3c), as well as correlations with self-reported criminal activity, right-wing authoritarianism, and social dominance orientation (Study 3d). We hope this scale will be useful in the study of police legitimacy, expanding the current literature, and improving police−community relations.