Inclusion Criteria:  Men and women age 18-65 Primary diagnosis of OCD YBOCS score of at least 18 at baseline Ability to understand and sign the consent form.  Exclusion Criteria:  Unstable medical illness based on history or clinically significant abnormalities on baseline physical examination or labs Current pregnancy or lactation, or inadequate contraception in women of childbearing potential Subjects considered an immediate suicide risk based on the Columbia Suicide Severity Rating Scale (C-SSRS) Past 12-month DSM-5 psychiatric disorder other than OCD Illegal substance use based on urine toxicology screening Initiation of psychological interventions within 3 months of screening Use of any other psychotropic medication Previous treatment with epidiolex Cognitive impairment that interferes with the capacity to understand and self-administer medication or provide written informed consent