Even after a quarter of a century, the groupthink hypothesis remains an influential framework for understanding the origins of group decision making fiascoes. Much of the original empirical evidence for this hypothesis was derived from a series of incisive qualitative studies of major policy fiascoes, including the ill-fated Bay of Pigs invasion and U.S. military escalation of the Vietnam War. In the 25 years since the groupthink hypothesis was first formulated, new evidence, including recently declassified documents, rich oral histories, and informative memoirs by key participants in these decisions have become available to scholars, casting new light on the decision making process behind both the Bay of Pigs and Vietnam. Much of this new evidence does not support Janis’s original characterization of these processes. In particular, it suggests that dysfunctional group dynamics stemming from group members’ strivings to maintain group cohesiveness were not as prominent a causal factor in the deliberation process as Janis argued. Instead, the evidence suggests that the decision making process was heavily influenced by how Presidents Kennedy and Johnson construed their options. Both Kennedy and Johnson tended to evaluate their alternatives primarily in terms of their political consequences, especially the desire to avoid what they construed as unacceptable political losses and potential damage to their reputations. Viewed in aggregate, this new evidence suggests that the groupthink hypothesis overstates the influence of small group dynamics, while understating the role political considerations played in these decisions. Thus, although both decisions may have been seriously flawed, the logic of this failure should be attributed to political psychological rather than social psychological processes.