An attempt was made to identify obsessive-compulsive disorder (OCD) subgroups based on differences in OCD related beliefs. OCD patients (N = 3 6 7) were assessed with the Obsessional-Beliefs Questionnaire prior to treatment. Individuals' scores on measures of inflated personal responsibility and the tendency to overestimate threat, perfectionism and intolerance of uncertainty, and over-importance and over-control of thoughts were subjected to cluster analysis. Support for both a simple and complex subgroup model was found (2-subgroup and 5-subgroup taxonomies). A low-beliefs subgroup was identified in both taxonomies. The low-beliefs subgroups reported scores on belief measures equivalent to scores reported for non-OCD comparison groups in earlier studies. Additional analyses were conducted to determine relations between belief-based and symptom subgroups. Significant relationships were found (e.g., Symmetry symptom subgroup membership was associated with membership in the Perfectionism/Certainty beliefs subgroup), although the shared variance was modest. Implications for understanding OCD heterogeneity and for cognitive theory are discussed.