Cognitive theorists propose that each anxiety disorder is associated with a specific tendency to overestimate the danger inherent in particular situations or internal states. Studies comparing anxious patients with non-patient controls have shown that several anxiety disorders are associated with elevated subjective estimates of the likelihood (probability) and cost of negative events. The present study focuses on social phobia and extends previous findings by: a) including a control group of equally anxious patients with another anxiety disorder and b) investigating the effects of successful cognitive and drug treatments on patients' probability and cost estimates. In line with cognitive theory, the results indicate that social phobia is associated with a specific elevation in subjective estimates of both the probability and cost of potentially negative social events. Reductions in overestimation occurred in successful cognitive and drug treatment and were closely related to the degree of symptomatic improvement in both treatments. Contrary to previous findings, there was no evidence that reductions in cost were more important than reductions in probability.