A measure of the extent to which the Kuder Occupational Interest Inventory (KOIS) was predictive of occupational membership for an individual was correlated with KOIS item and scale scores. KOIS items and scales were shown to moderate the 12 to 19 year predictive validity of the KOIS. Women with nontraditional interests were found to be relatively less predictable by the KOIS. THE classic validation model requires measurement of the association between a predictor and a criterion while ignoring intervening factors. Alternatively, methods have been developed to identify relatively enduring variables which affect validity, called &dquo;moderator variables&dquo;. Particularly, an inventory can serve as a moderator of its own validity. In the present study KOIS items and scales are shown to moderate the 12 to 19 year predictive validity of the KOIS.A wide range of variables may be moderators of vocational interest inventories: the appropriateness of the criterion, occupation engaged in, as reflected by job satisfaction (Strong, 1955;Zytowski, 1976); environmental factors, such as the job market; a lack of capacity to perform the occupation of one's interests because of inadequate intelligence, poor physical health or lack of skill in interpersonal relationships (Strong, 1955); lack of motivation to answer seriously (Note 1); demographic characteristics, such as sex, age, college enrollment, enrollment in a vocationally relevant curriculum, occupational level, and eventual entry into a science or technology course (Zytowski, 1976). Deviant subjects are not as predictable as more usual people. The 'The authors thank G. Frederic Kuder for making the data available to them.