In this chapter, we examine how the understanding of the nature and treatment of autism spectrum disorder (ASD) has evolved over the past decades. Advances in the field have been shaped by growing scientific knowledge as well as shifts in societal views, marking a progression from the widespread use of unethical and unsupported treatments to the increasing appreciation and integration of evidence-based practices and inclusive approaches. However, advising families in search for the best intervention to help their children with ASD is challenging, due to the proliferation of intervention options, difficulties accessing services, and the heterogeneity of intervention needs within the ASD population. Current knowledge and ongoing challenges in the area are discussed.