The current paper examines the dispositional and situational antecedents, as well as the attitudinal and behavioral consequences, of the frequency of upward and downward social comparisons. We predicted social comparison frequency would be influenced by uncertainty-related antecedents, and that social comparisons in organizations would be characterized by contrast, not assimilation, effects. A large and occupationally diverse sample of 991 employed adults was surveyed at three separate points in time over a 12-16 week period. Our results, based on structural equation modeling, indicated that (a) role ambiguity, task autonomy, and core self-evaluations were significant predictors of upward social comparison, (b) upward social comparison was significantly negatively related to job satisfaction and affective commitment, (c) downward social comparison was significantly positively related to job satisfaction and affective commitment, and (d) upward and downward social comparisons had significant positive and negative indirect effects on the frequency of job search behaviors, respectively. The findings are discussed in terms of their general implications for understanding the importance of directional social comparison processes in organizational settings. (Contains 1 figure and 5 tables.)