The decisions President Richard Nixon and his closest advisors made in the Watergate coverup were products of what Irving Janis calls "groupthink." Groupthink, a type of decision-making emphasizing unanimity over objective evaluation, develops when the decision makers (1) form a group of marked cohesiveness, (2) insulate themselves from outside groups and potential criticism, (3) lack an impartial leadership, (4) establish no norms for evaluating information, (5) share similar social and ideological backgrounds, and (6) experience situational stress from both within and without the group. An examination of participants' reports and White House transcripts suggests that Nixon, H. R. Haldeman, John Ehrlichman, John Dean, and John Mitchell formed just such a group, obsessively loyal to the President and isolated from outside opinions. Symptomatic of their use of groupthink, the President and his advisors shared illusions of invulnerability. Believing in the inherent morality of their efforts, they stereotyped critical out-groups as harmful. To preserve a sense of unanimity, members censored themselves and pressured others to concur with the group's policies. Further research on the decision-making process in the Watergate coverup could yield steps for identifying or avoiding the groupthink phenomenon. (MM)