Camarata highlights the impact that symptom hetereogeneity, overlap, and individual differences can have on the accurate early diagnosis of children with autism spectrum disorders (ASD) and measurement of treatment outcomes. Nevertheless, these individual differences may provide avenues for predicting individual responses to treatment with the view to prospectively matching children with ASD to treatments best-suited to meeting their individual needs. This commentary suggests that the behavioural characterstics that are critical to accurate early diferential diagnosis of ASD may be poor predictors of outcomes. However, factors that are not unique to ASD may in fact be good predictors of treatment outcomes. This commentary illustrates these points with reference to the results of recent studies demonstrating the problems, and possibilities, that individual differences currently present when it comes to understanding and promoting learning in children with ASD.