The current study examined the criticism component of expressed emotion (EE) and attributions in parents of adults diagnosed with schizophrenia/schizoaffective disorder (S/SA) or high functioning autism/Asperger's. Consistent with study hypotheses, parents of adults diagnosed with autism/Asperger's disorder exhibited lower levels of high EE-criticism than parents of adults diagnosed with S/SA. Moderate trends suggested that parents of adults diagnosed with autism/Asperger's disorder tended to make less blameworthy attributions towards patients than did parents of adults diagnosed with S/SA. A content analysis of parents' causal attributions was also conducted. The most common cause cited by both groups of parents was biological factors, suggesting that parents may be becoming more aware of scientific findings implicating biological factors, in conjunction with psychosocial factors, as a major cause of mental illness. (Contains 2 tables.)