Since its inception the validity of the most popular theory of group decision-making, Irving Janis’(1982) theory of groupthink, has been scrutinized. One major criticism is it lacks predictive validity due an overreliance on retrospective case studies of political fiascoes made by the American government (e.g., Bay of Pigs). The second criticism is it lacks empirical validity for failing to demonstrate the presence of two of its three predictors: cohesiveness and provocative situational context. As such, the contributions of this book to the emotions, groupthink, and decision-making literature are to illustrate: 1) using the Decision to Invade Iraq that a revised theory of groupthink is predictive and relevant, 2) that positive emotions such as hope precedes risky group decision-making processes, and 3) group polarization exacerbates group-level emotions and risky group decision- making, especially when the group lacks decision- making protocols. While the intention of this book is not to evaluate the Decision to Invade Iraq, the cumulative evidence to date strongly suggests that it is a classic case of groupthink.