Treatment trials for psychogenic nonepileptic seizures (PNES) are few, despite the high prevalence and disabling nature of the disorder. We evaluated the effect of cognitive behavioral therapy (CBT) on reduction of PNES. Secondary measures included psychiatric symptom scales and psychosocial variables. We conducted a prospective clinical trial assessing the frequency of PNES in outpatients treated using a CBT for PNES manual. Subjects diagnosed with video/EEG-confirmed PNES were treated with CBT for PNES conducted in 12 weekly sessions. Seizure calendars were charted prospectively. Twenty-one subjects enrolled, and 17 (81%) completed the CBT intervention. Eleven of the 17 completers reported no seizures by their final CBT session. Mean scores on scales of depression, anxiety, somatic symptoms, quality of life, and psychosocial functioning showed improvement from baseline to final session. CBT for PNES reduced the number of PNES and improved psychiatric symptoms, psychosocial functioning, and quality of life.