iCBT for Adult Obsessive-Compulsive Disorder

Inclusion Criteria: * Age between 18 and 75 * Internet access * Principal diagnosis of OCD, based on DSM-5 * Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) Total Severity Score \> 16 * Ability to communicate in Spanish * For participants taking psychotropic medication for OCD: at least eight weeks on stable medication and willingness to stay on the same medication/doses for the 12 weeks of the study Exclusion Criteria: * Estimated IQ \< 70, as per the Vocabulary subtest of the Wechsler Adults Intelligence Scale for Children (WISC) * Eight or more previous sessions of CBT for OCD with an experienced therapist during the last 12 months * Ongoing psychological treatment for OCD * Diagnosis of organic brain disorder, intellectual disability, autism spectrum disorder, psychosis, bipolar disorder, low-weight anorexia nervosa, or alcohol/substance dependence * Immediate risk to self or others (e.g., suicidality) * Inability to communicate in Spanish * Low motivation to participate (i.e., the patient does not believe the therapy will be helpful at all) * Insufficient time to work on the treatment (about 30 minutes per day)