In related literature, although various rater demographic characteristics, opportunity to observe and interpersonal affect have been considered in many studies, a small number of investigations has indicated the influence of interpersonal affect and opportunity to observe on ratings in multi- source assessment process. In this study, we investigated whether rater affect has a similar effect on the ratings from three sources in multi-source assessment process and whether there is an interaction between rater’s affect and the opportunity to observe the rate. All the white collar employees (39 persons) within a medium-sized manufacturing company participated in the study. The findings indicate that the influence of interpersonal affect on ratings was significantly greater in subordinate and peer feedback than in supervisor feedback.