Many countries involve lay people in legal decision making through jury systems, but critics question the competence of these decision makers in deciding trial outcomes. This chapter discusses the empirical literature examining lay participation in legal decision making, first exploring the mechanisms through which citizens around the globe participate in legal decision making. Then, the chapter reviews the theoretical models of juror and jury decision making, articulating the process jurors use in making decisions and how this translates to the group context of the jury. Next, the chapter turns to research on the competence of juries in making appropriate decisions, comparing decisions made by professional judges and lay people. Last, the chapter identifies new areas of inquiry in the empirical literature regarding lay participation in legal decision making that would benefit from further research.