This study examined the effectiveness of individual high-density exposure (2-3 weeks, all day) for panic disorder with agoraphobia (PDAG). Participants were 416 unselected patients with a primary diagnosis of PDAG who were treated by 52 therapists in 3 outpatient clinics of the Christoph-Dornier Foundation of Clinical Psychology in Germany. Results 6 weeks after the end of therapy and at the 1-year follow-up showed highly significant reductions in anxiety symptoms, anxious cognition, agoraphobic avoidance, general symptomatology, and depressive symptoms. Results did not differ significantly between the 3 outpatient clinics and are comparable with the average effect sizes reported by meta-analytic studies of controlled efficacy research, using selected patients and specifically trained therapists. Effectiveness was not dependent on duration of disorder, number of treatment sessions, and therapist experience. The study suggests that high-density exposure can be transported from research settings to the mental health field.