The effectiveness of "home-based" exposure and response prevention was assessed in a series of 11 subjects with obsessive-compulsive disorder (OCD). Patients received 24 treatment sessions in a range of natural settings and situations. Sixty-four percent of the patients responded to behavior therapy in these settings, and 36% achieved lasting improvements in their OCD symptoms. Implications for the impact on consumers of this seldom-used application of behavior therapy are discussed and some recommendations for future research are made.