While considerable research has focused on maladaptive perfectionism as a risk factor for social anxiety, little attention has been given to the mechanisms that mediate the effects. We integrated perfectionism with the bivalent fear of evaluation model of social anxiety to investigate 2 hypothesized mechanisms: hostile attribution bias and disqualification of positive social outcomes (DPSO). Specifically, we hypothesized that individuals with maladaptive perfectionism develop hostile attribution biases which then lead to DPSO, which in turn predisposes them to social anxiety. Participants were 242 individuals from the general population who completed measures of perfectionism, hostile attribution bias, DPSO, and social anxiety. A test of multiple mediators using bootstrapping supported the hypothesized multiple mediator models. The results suggested that maladaptive perfectionism predisposes an individual to social anxiety through hostile attribution bias and DPSO. The results further suggested that DPSO but not hostile attribution bias operates as an individual mediator in the perfectionism–social anxiety relationship. The findings from this study provide support for the bivalent fear of evaluation model of social anxiety; however, the use of a cross-sectional design limited our ability to find true cause-and-effect relationships.