The Obsessive Compulsive Cognitions Working Group (OCCWG) created the Interpretation of Intrusions Inventory (III) to measure appraisals (interpretations) of mental intrusions. Validation attempts by the OCCWG suggest that the three appraisal mechanisms hypothesized to comprise the III are better described as a single construct. The underlying factor structure of the III was investigated with university students (n = 307). Confirmatory factor analyses were conducted on the theoretically-derived three-factor model and on the empirically-derived one-factor model of the III. Both models failed to adequately fit the data. Thus, an exploratory factor analysis was conducted, which produced a two-factor model consisting of appraisals of Responsibility and Importance/Control of Thoughts. The new factors exhibited good predictive validity, as they predicted the severity of obsessive-compulsive symptoms and subtypes of obsessive-compulsive disorder (OCD).