This review evaluates five explanations for why social phobics perceive a discrepancy between performance requirements and their own abilities. There is little evidence to suggest that social phobia is associated with perfectionistic performance standards (possibility 1), perfectionistic standards in social situations (possibility 2), or perceptions of perfectionistic standards in others (possibility 3). Possibility 4, that social phobics set rigid performance standards, requires additional research. Support is provided for possibility 5, however, which proposes that social phobics perceive their own performance abilities negatively. Subsequently, it is concluded that low self-related beliefs account for the discrepancy between social phobics' perceptions of performance requirements, and their perceptions of their performance abilities. This conclusion is discussed in the context of contrasting models of social phobia, and implications for treatment are considered.