Just over 40 years have now passed since the landmark 3rd edition of the American Psychiatric Association Diagnostic and Statistical Manual—DSM-III (American Psychiatric Association, 1980). Before DSM-III appeared, there was no official recognition of autism and both clinical work and research suffered as a result (American Psychiatric Association, 1980); In the first article in this section Rosen and colleagues (Rosen et al., 2021) summarize that the rational for autism’s official recognition rested on several important and distinctive lines of evidence and despite some problems with the definition it significantly advanced work in the area. As Rosen and colleagues discuss important issues and areas of diagnostic controversy remain even in the face of attempts to produce better revised definitions of the condition. These controversies have to do with issues like gender and cultural issues, the complexities of Asperger’s disorder, and the broader autism phenotype even while the most recent name change to Autism Spectrum Disorder has been well received. In the next article Fombonne and colleagues (Fombonne et al., 2021) note the important advances and challenges that have come with official recognition and epidemiological research. As they emphasize, challenges include culturally based work and continued surveillance studies of autism but compared to what we knew back in 1980 knowledge has advanced markedly. The quality of outcome studies began to increase in both number and sophistication. As Howlin reviews (Howlin, 2021), the evolving ways in which autism has been conceptualized have had significant importance in planning for adult services and evaluating changes in outcome. Similarly, as Vivanti and Messinger discuss (Vivanti & Messinger, 2021) the official diagnosis of the condition has led to a number of important attempts to develop psychological models and theories of autism that can both guide research and may also have important implications for clinical work. The growing consensus on best approaches to diagnosis of autism has also significantly advanced work in the area of genetics; this work, first begun in the 1970’s, has now emerged as one of the major areas of research interest in the condition and, as Thapar and Rutter discuss (Thapar & Rutter 2020), there have been important implications for understanding the heritability of autism and its diagnostic boundaries. Similarly work on the neuroscience of autism has been significantly advanced as we now understand much more about some important basic aspects of brain functioning in ASD and have seen autism emerge as, in many ways, the prototypic disorder for the study of the social brain (McPartland et al., 2021).