Despite much psychological research regarding jury decision making, surprisingly little is known about the deliberation process that gives rise to jury verdicts. We review classic jury decision-making research regarding the importance of deliberation and more recent research, investigating deliberation and hung juries, that challenges the view that deliberation does not have an important impact on verdicts. We advocate greater attention to potential cognitive processes during deliberation that might explain the transition between predeliberation preferences and a jury's ultimate verdict. We then review cognitive work in the group context generally, and the jury context specifically, illustrating the promise of a cognitive perspective on jury deliberation. Finally, we identify cognitive phenomena likely to be particularly valuable in illuminating deliberation behavior.