Purpose <p>Fear of negative evaluation is a diagnostic criterion for social anxiety disorder (SAD). Research demonstrates this may not always occur in autistic individuals who have other markers of SAD. We aimed to characterize fear of negative evaluation in autistic children utilizing a sample of 239 autistic youth ages 10–16.</p> Methods <p>Participants completed self-report questionnaires of social anxiety and fear of negative evaluation. They also participated in a conversation task coded by trained observers to measure social anxiety.</p> Results <p>Although self-reports of social anxiety and fear of negative evaluation were strongly correlated, they did not match in-the-moment coding of social anxiety from trained observers; this may be partially explained by differences between state and trait experience and the conversational environment. Furthermore, greater levels of autistic traits related to higher levels of social anxiety and to fear of negative evaluation.</p> Conclusions <p>Fear of negative evaluation, which is the primary cognitive process involved in social anxiety, was strongly associated with social anxiety in this autistic sample of youth.</p>