Management scholars and practitioners often believe that individuals and organizations benefit by trusting their work contacts. (Husted, 1998; Sonnenberg, 1994) Trust is generally viewed as "good" and imperative to a modern functioning economy (Blau, 1964; Hosmer, 1995; Zucker, 1986) Consequently, scholars and practitioners have given scant attention to the "downside" of trust, despite the fact that trust involves taking risk under conditions of uncertainty (Rousseau et al., 1998) Recent corporate scandals show that people suffer when they misplace trust in untrustworthy organizations and individuals. This paper develops a model of the causes and consequences of "over-trust," which we define as a state where a trustor's trust exceeds that which is warranted given the conditions. The antecedents of overtrust related to characteristics of the trustee, the trustor, and situational characteristics. We examine the role played by self-monitoring and perceived power base of the trustee as two key trustee characteristics. Among trustor characteristics, we examine the role (played by trustor's core evaluation, core values). based on cultural affiliation), prior experiences with trustees, and use of habitual thinking behavior. Under characteristics of the situation, we examine the role played by uncertainty inherent in the situation, perceived threat from the context, degree of task interdependence, and organizational systems and routines. Next, we examine three consequences of over-trust - leniency in judging the trustee, delay in perceiving exploitation, and increased risk-taking. We conclude our paper by developing a set of guidelines that organizational members may employ to avoid over-trust.