Two important components of the Clark and Wells (in Social phobia: diagnosis, assessment, and treatment. Guilford, New York, pp 69–93, 1995) model of social phobia are ruminative processing and maladaptive self-beliefs (high standard, conditional and unconditional beliefs). In a longitudinal design, we hypothesised that rumination at Time 1 would be positively associated with the strength of each of the belief types at Time 2 (while controlling for depression, general anxiety, social anxiety and strength of belief types at Time 1). For our sample of undergraduates (N = 180), the average time between Time 1 and Time 2 was 8.84 days. Contrary to predictions, rumination at Time 1 was not uniquely related to the high standard beliefs at Time 2. Consistent with predictions, higher levels of rumination at Time 1 uniquely predicted stronger conditional and unconditional beliefs at Time 2. These results highlight the link between ruminative processing and specific maladaptive self-beliefs, and suggest that treatments of social phobia need to explicitly target rumination.