The present study sought to examine patterns of habituation in exposure and response prevention (ERP) treatment of compulsive hand washing. Sub-clinical compulsive washers (n=27) with illness or non-illness primary threats were compared in order to detect potential differences in response to a single session of ERP. Changes in anxiety, disgust, and urge to wash were analyzed, and significant reductions in both anxiety and disgust were noted. Urge to wash significantly declined among washers primarily concerned with illness; among those concerned with non-illness threats, urge to wash did not significantly decline. Moreover, anxiety was found to decline when controlling for disgust and vice versa. Lastly, when both anxiety and disgust were entered into a model predicting changes in urge to wash, anxiety but not disgust predicted urge to wash for those with illness-related threats; for washers with non-illness threats, the findings were the reverse. Several clinical and theoretical implications are discussed.