Considerable research has focused on understanding why group discussion promotes cooperation in social dilemmas (e.g., Chen & Komorita, 1994; Dawes, McTavish, & Shaklee, 1977; Kerr & Kaufman-Gilliland, 1994; Orbell, van de Kragt, & Dawes, 1988; Sally, 1995). Several causal explanations (i.e., group identity, commitment-making, norms) have been proposed and tested experimentally. This chapter reviews the literature on group discussion and cooperation to further explore why and how face-to-face discussion exerts this robust effect. We also extend the current conversation by considering whether various forms of electronic technology (e.g., e-mail, Internet conferencing) allow small groups to capture the proven benefits of discussion without the limiting requirement of collocation. We report preliminary findings from three experimental studies in our lab that investigate some unanswered questions. Our literature review and conceptual analysis suggest some important theoretical implications for understanding discussion’s effect in social dilemmas and a promising agenda for future research.