The purposeof this paper is to develop a measurement model of the sentiments of police legitimacy among São Paulo citizens. National survey-based research on public attitudes towards the legal authorities commonly adoptsan operationalist approach, ignoring the gap between concepts and survey questions. We contribute substantively to this research field by developing a measurement model of police legitimacy, which is conceptually defined as a normatively grounded duty to obey the police and a moral alignment with the police. Using data from a representative survey of eight regions of the city ofSão Paulo in 2017, we performed a second-order confirmatory factor analysis. Subsequentely, we estimated a structural equation model centered on the legitimacy construct so as to validate the measure. Policy implications of both the concept and the measurement of police legitimacy are discussed.