Social phobia is a very prevalent and debilitating disorder, with public speaking anxiety being the most common fear among socially phobic individuals. Although there are a number of effective psychosocial treatments for social phobia (e.g., cognitive-behavioral treatments and exposure therapy) very little is known about the underlying mechanism of therapeutic change (i.e., the mediators of change), and the variables that are predictive of treatment outcome (i.e., the moderators of change). Furthermore, it is unclear why treating individuals for their public speaking anxiety can generalize to other untreated social fears.