This study examined parent and teacher rating correspondence of adaptive and challenging behaviours for children with autism spectrum disorders (ASDs) enrolled in an early intervention program. Data were collected on the Behaviour Assessment System for Children, second edition (BASC-2; n = 22), and Vineland Adaptive Behaviour Scales, second edition (VABS-II; n = 28). Adaptive behaviour ratings generally demonstrated high parent–teacher correlations, while challenging behaviour ratings demonstrated relatively low correlations. Only adaptive skills on the BASC-2 showed significant mean parent–teacher differences, with parent ratings suggesting greater impairment. Results suggest that clinicians should consider gaining both parent and teacher perspectives on a child's challenging behaviour, but that a single informant measure of adaptive behaviour, either parent or teacher, may be sufficient after initial assessments are completed.