The analyses confirm that procedural justice judgments affect police legitimacy, which in turn influence both cooperation with police and compliance with the law. There was considerable support for Tyler’s arguments when assessing the directional accuracy of the revised measures in a regression context. The mounting evidence in support of Tyler’s processed-based model is reason for optimism and should invite additional assessments by social and behavioral scientists. In 2003 and 2004, Tyler argued that treating citizens respectfully and making fair decisions enhanced police legitimacy, which in turn facilitates citizen cooperation during and after police encounters and promotes long-term compliance with the law. This argument was known as Tyler’s process-based model. However, there is the need to assess and, if necessary, refine the scales commonly used to study police-citizen relations and, in particular, to test the key propositions of the process-based model of policing. Prior tests of Tyler’s process-based model of policing have left basic measurement questions unanswered. With a sample of 432 adults from a nationwide telephone survey conducted in 2005, factor-analytic procedures were used to develop more valid scales and to test process-based model hypotheses. Tables, appendix and references