The psychometric properties of the Compulsive Activity Checklist (CAC) were examined in a sample of obsessive compulsives (OCD), anxiety disordered (AD) patients, and non-psychiatric subjects (NP). All but 9 of the 38 CAC items significantly discriminated among groups, yielding correct classification rates of 71% when OCDs were compared with ADs and 84% when OCDs were compared with normals. Internal consistency alpha was high (0.95), but nine item-total correlations for OCD subjects fell below 0.40. A 28-item abbreviated scale (CAC-R) was developed based on the above findings. Preliminary analyses of the CAC-R on a normal sample indicated that this version is an improvement over the longer version and may be a viable alternative to the 18-item French one. It appears that the original CAC can be shortened with little loss of validity. However, substantial reductions may reduce the clinical utility of an instrument assessing a disorder with such widely diverse manifestations.