The present study examined the degree to which social anxiety predicts aggression in children with high functioning autism spectrum disorders (HFASD, n = 20) compared to children with Social Anxiety Disorder (SAD, n = 20) or with Oppositional Defiant Disorder or Conduct Disorder (ODD/CD, n = 20). As predicted, children with HFASD reported levels of humiliation/rejection fears commensurate with children with SAD and exhibited aggression at levels commensurate with ODD/CD, and a curvilinear relationship between social fears and aggression was found in the HFASD group only. Results indicate the possibility of an optimal level of social-evaluative fears that is unique for children with HFASD; too little social fear or too much may contribute to problems with aggression.