To test the causal status of responsibility in obsessive-compulsive disorder (OCD), an experiment was executed in which responsibility was experimentally manipulated. OCD patients, non-OCD anxiety controls, and non-patients executed a classification task in either a high or a low responsibility (LoRes) condition. Subjective ratings related to danger and responsibility indicated that the manipulation was successful. Subjective OCD-like experiences and checking behaviors were higher in OCD patients in the high responsibility (HiRes) condition than in all other groups. Although the checking subscale of the Padua Inventory correlated with subjective ratings in the OCD patients in the HiRes condition, it was not associated with checking behaviors. The results confirm the hypothesis that responsibility plays a causal role in CCD.