From the abstract: The autism spectrum disorder (ASD) diagnostic classifications, according to the DSM-5, include a severity rating. Several screening and/or diagnostic measures, such as the autism diagnostic and observation schedule (ADOS), Childhood Autism Rating Scale (CARS) and social responsiveness scale (SRS) (teacher and parent versions), include an assessment of symptom severity. The purpose of this study was to examine whether symptom severity and/or diagnostic status of preschool-aged children with ASD (N = 201) were similarly categorized on these measures. For half of the sample, children were similarly classified across the four measures, and scores on most measures were correlated, with the exception of the ADOS and SRS-P. While the ADOS, CARS, and SRS are reliable and valid measures, there is some disagreement between measures with regard to child classification and the categorization of autism symptom severity.