Intolerance of uncertainty has been related to increased worry in recent conceptual models of Generalized Anxiety Disorder (GAD). The present study examines the relationship between a measure of intolerance of uncertainty, the Intolerance of Uncertainty scale (IU), and behaviors associated with GAD, such as slowness of execution and amount of evidence required before decision making. A total of 49 individuals participated in the study. Three experimental tasks varying in level of ambiguity and difficulty were used. The analyses show a positive correlation between scores on the IU and number of cues required before responding in a moderately ambiguous inference task. However, scores on the IU were not significantly related to responses in an unambiguous task (regardless of the level of difficulty) or in a highly ambiguous task. The results suggest that high worriers have a lower threshold of tolerance of uncertainty for intermediate levels of ambiguity. The results are discussed in terms of theoretical models of GAD.