Two studies are reported which examined the content of beliefs about self-attributes in social phobia, and the level of certainty with which these beliefs are held. The results of both studies indicated that individuals with social phobia held less positive beliefs about their personality characteristics in comparison to non-anxious individuals. In addition, social anxiety was associated with reduced subjective confidence in self-descriptiveness ratings for personality attributes (Study 1), as well as longer reaction times in making self-descriptiveness decisions relative to general decisions about trait adjectives (Study 2). The association between social anxiety and reduced certainty in negative attribute ratings was evident after controlling for depression, general anxiety, stress, and the extent to which negative attributes were endorsed as being self-descriptive. Results are discussed in terms of the potential role that reduced self-concept certainty may play in social phobia.