Intensive treatments for youth obsessive-compulsive disorder (OCD) are important and underresearched. This study used three adolescent cases to assess the preliminary efficacy of an intensive treatment combining acceptance and commitment therapy (ACT) with exposure and response prevention (ERP) for OCD. Participants received intensive treatment for 15 hours per week for three weeks. Assessments were collected at pre-treatment, weekly during treatment, and at posttreatment. All participants ended treatment in the mild range of OCD severity with 32-60% reductions in symptoms. Participants also reported notable improvements in psychological flexibility and ended treatment in the non-clinical range of depression, anxiety, and stress. These results indicate promise and preliminary support for the use of ACT+ERP in intensive settings for adolescents with OCD. This paper focuses on the clinical application of these techniques.