The proposed research explores the origins and consequences of systematic distortions in people's perceptions of the thoughts, attitudes, and behaviors of others. The long-term objective of the proposal is to document when and why discrepancies arise between objective and perceived group consensus and how these discrepancies influence individual and group functioning. Our special focus here, as in our previous work, is on the phenomenon of pluralistic ignorance: the mistaken belief that one's private thoughts. feelings, and behaviors are different from those of others, even though one's public behavior is identical. The proposal's objectives will be pursued through an interrelated program of experimental and correlational studies. Study 1 examines the role that pluralistic ignorance plays in the creation and perpetuation of campus norms promoting excessive alcohol use, and tests the effectiveness of a pluralistic- ignorance-based intervention for changing these dysfunctional norms. Study 2 extends the application of pluralistic ignorance to the context of inter-group relations and examines its role in inhibiting inter-racial contact on campus. Studies 3 shows that pluralistic ignorance involves not only the mistaken perception that one is different from others but also the mistaken perception that others are all alike. Studies 4 and 5 seek to demonstrate that pluralistic ignorance accompanies and shapes the development of social attitudes in children. Studies 6 and 7 examine the role that pluralistic ignorance plays in two well-established social influence phenomena: group polarization and minority influence. Study 8 tests the hypothesis that pluralistic ignorance contributes to the tendency of people to perceive themselves as experiencing less discrimination than other members of their social category. Studies 9 and 10 extend the analysis of illusory uniqueness effects to judgment and decision making domains. This program of research will contribute to an understanding of (a) the conditions under which people develop erroneous perceptions of deviance, and (b) the relation of perceived deviance to psychological adjustment and the perpetuation of unhealthy and unpopular social practices.