Recent work in performance appraisal has focused on the cognitive operations involved in a rating task, but has neglected the influence of affect. The purpose of the present study was to examine the process by which affect influences evaluations and to examine the impact of affeet on outcome variables. A categorization-based model of the rating process was developed that included the influence of affect. According to the model, affect was postulated to influence the categorization process at the superordinate level. The model also postulated that the classification would then influence the processing of subsequent information. To test predictions derived from the model, the present study simulated a work situation. Subjects were required to learn materials, train confederates, and then observe and evaluate confederate's videotaped performance. The impact of affect and item type was examined on process measures and the impact of affect and performance was examined on outcome measures. The results showed that affect biased leader evaluations in the form of leniency and severity. Signal detection analysis indicated that response bias may have been the cognitive mechanism underlying this effect. Leaders attributed non-performed behaviors to confederates in a category consistent manner. Path analysis showed that affect has direct and indirect effects on performance evaluations. The theoretical and applied considerations of the study's findings are discussed and future research directions are highlighted. / Ph. D.