This study examined whether personality disorder status and beliefs that characterize personality disorders affect response to cognitive therapy. In a naturalistic study, 162 depressed outpatients with and without a personality disorder were followed over the course of cognitive therapy. As would be hypothesized by cognitive theory (A. T. Beck & A. Freeman, 1990), it was not personality disorder status but rather maladaptive avoidant and paranoid beliefs that predicted variance in outcome. However, pre- to posttherapy comparisons suggested that although patients with or without comorbidity respond comparably to "real-world" cognitive therapy, they report more severe depressive symptomatology at intake and more residual symptoms at termination.