Language assessment in children with autism spectrum disorder: Concurrent validity between report-based assessments and direct tests

•Parent and preschool teacher ratings have high concurrent validity when compared to direct tests.•The CDI can be a supplement to direct tests of language in children with autism.•The results strengthen the psychometric properties of the CDI W–G.

Impairments in expressive and receptive language are common in individuals with autism spectrum disorder (ASD). Therefore, the importance of language assessment is emphasized in e.g. DSM-5. Thus, studies addressing the validity of different language measures are important. Parents and preschool teachers of 55 children diagnosed with childhood autism separately filled out the Communicative Development Inventory (CDI), a widely used report-based assessment of language. The children were also tested with the two standardized direct language tests: Reynell Developmental Language Scales (RDLS) and Mullen Scales of Early Learning (MSEL). Concurrent validity across the three measures was investigated. The results suggested very high agreement between the measures, and this was found regardless of whether parents or preschool teachers filled out the CDI. Given the difficulty in testing children with low language levels, as often is the case in young children with ASD, this study shows that several valid measures are available for measuring expressive and receptive language.