Perceived control has been proposed to be a general psychological vulnerability factor that confers an elevated risk for developing anxiety disorders, but there is limited research examining perceived control during cognitive-behavioral therapies (CBT). The present study examined whether treatment resulted in improvements in perceived control, and the indirect effects of CBT on changes in symptoms of obsessive-compulsive disorder, social phobia, generalized anxiety disorder, and panic disorder via changes in perceived control. Participants (n = 606) were a large clinical sample presenting for treatment at an outpatient anxiety disorders clinic. Participants completed a series of self-report questionnaires and a structured clinical interview at an intake evaluation and at two follow-up assessments 12 and 24 months later, with the majority of participants initiating CBT between the first two assessments. Results of latent growth curve models indicated that individuals initiating CBT subsequently reported large increases in perceived control and significant indirect effects of treatment on intraindividual changes in each of the four anxiety disorders examined via intraindividual changes in perceived control. These results suggest that the promotion of more adaptive perceptions of control is associated with recovery from anxiety disorders. Furthermore, the consistent finding of indirect effects across the four anxiety disorders examined underscores the transdiagnostic importance of perceived control in predicting CBT outcomes.