Accumulating evidence supports the premise that fear of evaluation in general is important in social anxiety, including fear of positive evaluation (FPE) as well as fear of negative evaluation (FNE). This study tested various hypotheses pertaining to a novel, expanded conceptualization of social anxiety involving these two distinct fears: the bivalent fear of evaluation (BFOE) model. Responses from a large undergraduate sample (N = 585) were examined. In addition, responses from a subsample of participants qualifying for a probable diagnosis of social anxiety disorder (SAD; n = 133) were examined, via mediational analyses, for potential mechanisms underlying FPE within highly socially anxious individuals. FPE exhibited a unique and significantly stronger relationship with concerns of social reprisal due to making positive impressions than did FNE. FPE related uniquely and negatively to trait positive affect/automatic thoughts, whereas FNE, FPE, and social anxiety all related uniquely and positively to trait negative affect/automatic thoughts. FPE, FNE, and social anxiety all related uniquely and positively to disqualification of positive social outcomes (DPSO). However, FPE related most strongly to DPSO attributions at the level of the self, and these attributions mediated the relationship between FPE and negative automatic thoughts in an analog clinical sample. Concerns of social reprisal due to making positive impressions on others mediated the relationship between FPE and DPSO attributions to others in an analog clinical sample. The obtained findings replicate and extend support for the BFOE model of social anxiety. Implications for the theoretical conceptualization and treatment of SAD are discussed.