Citizen cooperation with the police can have an important bearing on how effective the police are in performing their duties. Without cooperation, suspects disappear, leads unravel, arrests plummet, and cases fail to materialize. In those low-income communities where citizens tend not to report crime, the crime rate is nearly always high (La Vigne, Fontaine, & Dwivedi, 2017), whereas citizens who report victimization experiences to the police are less likely to be victimized in the future than those who do not report victimization experiences to the police (Ranapurwala, Berg, & Casteel, 2016). When victimization experiences are not reported to the police, criminals become emboldened and their inclination to believe they are above the law grows even stronger. Finding ways to encourage the public to cooperate with the police and other law enforcement officials is therefore of cardinal significance when it comes to improving police effectiveness. First, however, we must identify the factors that motivate the public to cooperate with the police. Two such factors, perceived police procedural justice and police legitimacy beliefs, were the focus of the current investigation. This investigation will use the meta-analytic method to examine the univariate associations between procedural justice, legitimacy beliefs, and cooperation with the police in studies conducted over the past 28 years.