Abstract: This chapter reviews the evidence on whether procedurally just treatment of citizens by agents of the criminal justice system (CJS), usually the police, has the effect of increasing the citizen’s compliance with the law. There are many operational definitions of procedurally just treatment, but all share the common characteristics of CJS agents treating citizens with respect and affording them the opportunity to explain themselves. In brief, we find that perceptions-based studies consistently show that citizen perceptions of procedurally just treatment are closely tied to perceptions of legitimacy of the police, and that, with only a few exceptions, perceptions of legitimacy are strongly associated with legal compliance. Perceptions, however, cannot be directly manipulated. What can be manipulated are policies designed to improve procedurally just treatment of citizens. What has not yet been established is the necessary requirement for such policies to be effective in improving compliance, namely that policy changes are effective in changing procedurally just treatment of citizens by police and other CJS agents and that such changes are effective in triggering the causal chain underlying the theory of procedural justice: improvements in actual treatment lead to improved perceptions of procedurally just treatment, which in turn leads to improved perceptions of legitimacy, which in turn increases legal compliance. In light of this conclusion, policy implications and suggestions for future research are discussed.