Abstract
Five objective scales for diagnosis of autism are evaluated with reference to psychometric criteria of reliability (test-retest, interrater, internal consistency) and validity (content, construct, concurrent, discriminant). The five scales are the Diagnostic Checklist for Behavior Disturbed Children (Form E-2), Behavior Observation Scale for Autism, Behavior Rating Instrument for Autistic and Atypical Children, Autism Screening Instrument for Educational Planning, and Childhood Autism Rating Scale. Although all scales have strengths and weaknesses, the Childhood Autism Rating Scale emerges as the strongest scale in terms of demonstrated psychometric properties.