Background: Adults with autism experience high rates of social anxiety disorder (SAD). Cognitive models of suggest that anticipatory (AP) and post-event processing (PEP) develop and maintain SAD symptoms. These models underpin gold standard treatment. It is unclear if the cognitive model for SAD applies to an autism population. In addition, there is little understanding of how these symptoms are experienced by adults with autism. Aims: To examine whether the cognitive model of SAD is relevant for adults with autism, as indicated by correlations between SAD and cognitive maintenance factors. The second aim was to explore how adults with autism describe their experience of anxiety in social situations. Design: A mixed method approach was used. Participants (n = 30) completed questionnaires about characteristics of autism, SAD, AP and PEP. Bivariate correlations were used to investigate the relationship between cognitive processes and SAD. Partial correlations were used to explore relationships between SAD and cognitive processes while controlling for autism-specific language difficulties. Participants (n = 8) also completed a semi-structured interview about their social experience, associated anxiety and how any anxiety was managed. Thematic analysis was used to analyse responses. Results: Participants reported high levels of SAD, AP and PEP. There was no significant relationship between SAD and autism symptoms. While AP and autism were significantly positively correlated, exploratory analysis did not indicate a clear relationship between AP, PEP, SAD and autism. Results of thematic analysis indicate anxiety in social situations causes significant impairment, with distressing thoughts before and after social interaction. Conclusions: Results provide qualitative evidence that the Clark and Wells (1995) model of SAD is relevant for adults with autism. Further research is necessary to investigate the relationship between cognitive styles, such as intolerance of uncertainty, with SAD and autism. Adults with autism may benefit from CBT for SAD alongside strategies to structure interactions and the environment.