Outpatients with a primary DSM-III axis I diagnosis of obsessive-compulsive disorder (OCD: N = 93) were randomly assigned to one of three treatment groups: One group (N = 30) received 24 sessions of behavioral group therapy over a 12-week period; a second group (N = 31) received 24 individual behavior therapy sessions over the same treatment interval; and members of a control group (N = 32) received 24 individual sessions of progressive muscle relaxation. The Yale-Brown Obsessive-Compulsive Scale was administered before treatment at 2-week intervals during treatment, and at 6-month follow-up to measure changes in distress caused by OCD symptoms. The Beck Depression Inventory and the Self-Rating Anxiety Scale were also administered at pretreatment, posttreatment, and 6-month follow-up. Both individual and group interventions proved to be equally effective at reducing distress caused by OCD symptoms, general depression, and anxiety by the end of treatment, although patients in the individual behavior therapy condition demonstrated faster reductions in OCD symptom severity. Patients in the group and individual behavioral interventions were able to maintain their gains at 6-month follow-up. Implications of these findings for outpatient treatment are discussed.