The purpose of this mixed-method study was to examine racial differences in parental beliefs and concern about autism spectrum disorder (ASD) versus clinical judgment. The sample included 489 children with ASD undergoing their first ASD evaluation. Parent belief that their child had ASD was highest among parents of White children. White children whose parents believed the child had ASD had lower ASD severity. Parents of Black/African American and Hispanic children were more likely to report communication concerns than parents of White children. Parental concern about social communication was related to higher ASD severity for Hispanic children. Implications for diagnostic processes are discussed.