the existence of intolerance of uncertainty (iu) about ambiguous social information in individuals with social anxiety has only recently begun to be explored by researchers, whereas the cognitive mechanisms whereby iu might contribute to social anxiety have thus far not been empirically investigated. the purpose of this study was threefold: to examine whether iu contributes significant variance in social anxiety severity above and beyond that accounted for by fear of negative evaluation, anxiety sensitivity, and depression; to investigate whether social anxiety severity is associated with greater levels of iu and a greater tendency to interpret ambiguous social events negatively; and to examine whether fear of negative evaluation and negative interpretation bias mediate the relationship between iu and social anxiety. two-hundred and ten undergraduate 世界杯2022赛程表淘汰赛 from 阿根廷vs墨西哥竞猜 completed part 1 (online) of the study and 66 participants from the initial sample completed part 2 (in-lab). results indicated a significant relationship between iu and social anxiety independent of all other variables. iu was found to have an additive and specific effect on social anxiety severity, with increasing levels of uncertainty intolerance corresponding with more intensified symptoms of social anxiety. however, irrespective of anxiety severity level, participants with social anxiety made more negative interpretations of ambiguous social events than controls, entailing that this negative interpretation bias is a core cognitive appraisal process among these individuals. as expected, fear of negative evaluation mediated the association between iu and social interaction anxiety, as well as the relationship between iu and performance anxiety. negative interpretations of ambiguous social information, however, only mediated the relationship between iu and social interaction anxiety. limitations and implications of study findings are discussed from a theoretical, methodological, and clinical perspective.