This study consists of a screening period that contains a 90-minute psycho-educational session and treatment period of up to 5 weeks. During the treatment period, patients will receive ten 60-minute CBT/ERP sessions held twice weekly. At the end of each session, patients will receive a 50 mg dose of DCS. Following the administration of the DCS, patients will be asked to do their best not to ritualize and remain on the Children's Day Unit, where they will be observed and report to the research team if any ritualization has occurred. At the end of study participation, all participants will be offered 10 additional sessions of twice-weekly ERP without DCS administration. All participants will then complete a follow-up visit at 10 weeks after baseline.