Defined expansively as the exchange of politically relevant justifications, political deliberation occurs at many sites in the democratic system. It is also performed by several different types of actors. Here, we review political deliberation based on who is deliberating and what role these deliberations play in making binding decisions. First, ordinary citizens frequently deliberate in informal settings. While these discussions often fail to live up to the standards outlined by deliberative theorists, they typically correlate with other democratic goods, such as increased political participation. Second, there have been several attempts in recent years to construct the conditions necessary for quality deliberation among citizens by organizing small-group discussions in semi-formal settings. Proponents of such discussions argue that they promote a variety of democratic goods, such as political knowledge and better-justified political decisions, and as such should be incorporated into the formal policymaking process. However, critics of these procedural innovations hold that a more deliberative society is unrealistic or, alternatively, that deliberation is not without drawbacks on its own terms. Third, in a limited number of cases, citizens’ deliberations are formally embedded in democratic institutions, serving to advise voters and politicians or directly leading to binding decisions. Finally, political elites deliberate frequently. Opinion leaders attempt to and often succeed in shaping the discourse around issues, while elected officials, bureaucrats, and judges formally deliberate before making almost every binding decision. Surprisingly, though these deliberations happen frequently and likely have substantial effects on policy, they are probably the least studied in the political system, though recent breakthroughs in text analysis offer a path forward to analyzing deliberation among elites more systematically.