BACKGROUND: Cognitions play an important role in the development and maintenance of social anxiety disorder (SAD). METHODS: To investigate whether changes in cognitions during the first six sessions of exposure therapy are associated with treatment outcome, we assessed reported self-focused attention, self-efficacy in social situations, and estimated social costs in 60 participants (Mage = 36.9 years) diagnosed with SAD who received in vivo or virtual reality exposure therapy. RESULTS: Patients demonstrating a greater decrease in estimated social costs during treatment reported greater improvement of their social anxiety symptoms following both forms of exposure therapy. While changes in self-focused attention and social self-efficacy during treatment were significantly associated with treatment outcome when examined individually, these changes did not significantly predict symptom improvement beyond social costs. CONCLUSIONS: Changes in estimated social costs during treatment are associated with improvement of social anxiety symptoms after exposure therapy. Future research needs to further investigate estimated social costs as a predictor in relation to other cognitive variables.