School psychologists who contribute to the assessment of children with an autism spectrum disorder (ASD) are required by various Australian state government authorities to use standardised testing of cognitive skills, adaptive behaviour and some autism-based symptomatology to demonstrate the eligibility of those children for support funding in the school environment. However, this process does not always address the needs of parents and teachers for detailed and particular analysis of the reasons for the pervasive behavioural difficulties often shown by children with an ASD. Such difficult behaviour has been shown to contribute to high levels of stress among caregivers and often prevents the child with an ASD from successful school inclusion. Therefore, it would be advantageous for parents and teachers to have access to information obtained from an analysis of the child's behavioural difficulties as one outcome of the formal testing process that is conducted to examine the possible presence of an ASD. This paper presents a brief example of how a basic behavioural investigation might be incorporated into the assessment of children with a suspected ASD.