This study examined how differences in magnitude of stimuli across two categories stimuli affected preference when two different response requirements were incorporated into the preference assessments. Four adults with intellectual disabilities participated in the study. In Phase 1, one preferred leisure activity and one preferred edible stimuli were identified for each participant. In Phase 2, preference for the preferred leisure activity and preferred edible items were evaluated across two different magnitudes (high and low). In Phase 3, a reinforcer assessment was attempted to determine if there was a difference in the reinforcing properties of the preferred items as a function of magnitude. However, all participants responded at ceiling levels in a no reinforcement baseline. Thus, in Phase 4, the same from Phase 2 were presented with a work requirement component between the selection response and delivery of the selected stimulus during the preference assessment. The results of this study suggested that stimuli identified as high preferred when there was no response requirement also were identified as high preferred when there was a response requirement. However, fewer stimuli were selected when the response requirement was included, suggesting that adding a response requirement to the preference assessment may enhance the predictive validity of those assessments in identifying reinforcers. Key words: preference rank, type of preference, stimulus magnitude, reinforcing effects, leisure and edible stimuli