Interventions that are based on scientific principles of applied behaviour analysis (ABA) are recognised as effective treatments for children with autism spectrum disorder (ASD) by many governments and professionals (Office of the Surgeon General, 2000; Ontario IBI Initiative, 2002). However, many still view ABA as one of many treatments for autism and contend that it should be part of an eclectic mix of interventions. This paper addresses this issue by outlining what ABA is and how ABA is related to the array of treatments for ASD. With approximately 1 in 100 children diagnosed with ASD, it is important for professionals to understand ABA accurately.