International consensus has been achieved on the existence of several dysfunctional beliefs underlying the development and/ or maintenance of the Obsessive-Compulsive Disorder (OCD). Nevertheless, questions such as the dimensionality of the belief domains and the existence of OCD-specific dysfunctional beliefs still remain inconclusive. The present paper addresses these topics through two different studies. Study 1: A series of confirmatory factor analyses (N = 573 non-clinical subjects) were carried out on the Obsessive Beliefs Spanish Inventory-Revised (OBSI-R), designed to assess dysfunctional beliefs hypothetically related to OCD. An eight-factor model emerged as the best factorial solution: responsibility, over-importance of thoughts, thought-action fusion-likelihood, thought action fusion-morality, importance of thought control, overestimation of threat, intolerance of uncertainty and perfectionism. Study 2: The OBSI-R and other symptom measures were administered to 75 OCD patients, 22 depressed patients, and 25 non-OCD anxious patients. Results indicated that, although OCD patients differed from their non-clinical counterparts on all of the OBSI-R subscales, no evidence of OCD-specificity emerged for any of the belief domains measured, as the OCD subjects did not differ from the other two clinical groups of patients.