This study explores the effects of different structures of accountability on the development of groupthink. Specifically, the differences between individual and collective accountability are examined and contrasted to a condition with no accountability. The groupthink phenomenon can be differentiated into collective avoidance, arising from a pessimistic perception of a decisional issue, and collective overoptimism. It is argued that structures of accountability can either promote or reduce groupthink, depending upon the way group members perceive the decisional issue. We tested the hypothesis that accountability can prevent the collective‐avoidance type of groupthink, and that individual accountability will be more effective in doing so than collective accountability, by preventing the possibility to “hide in the crowd.” The results confirm that under conditions conducive to collective avoidance, individual accountability is more effective in reducing groupthink‐like tendencies than collective accountability. However, group members expecting to be collectively responsible still display less symptoms of groupthink than control groups. In particular, accountability makes groups display more difficulty to reach consensus, stimulates group members to try to influence the decision making, results in a more equal dispersion of influence within the group, and in less risky decisions. Some methodological concerns regarding research on groupthink and accountability, and the implications of the findings for future research in this area are discussed.