Psychological phenomena have long been a focus of research on democratic deliberation, particularly concerning policy knowledge and attitudes and other issues addressed in conventional scholarship on political psychology. Yet in recent years, the subject matter of psychological research on deliberation has expanded to include a wider array of issues, ranging from lay conceptualizations of deliberation, to phenomena not foregrounded in traditional political psychology scholarship, including emotions, social identity, communication goals, relational schemata, and social learning. This essay summarizes key findings from prior research on psychological dimensions of deliberation, and then delineates recent deliberative scholarship that explores a broader range of psychological phenomena. Finally, this essay introduces the seven new articles that make up this special issue. These articles offer novel theoretical and empirical insights on a number of current themes concerning psychological aspects of deliberation, while expanding knowledge concerning established areas of inquiry.