The Guest Editors have assembled expert authors to cover the full clinical span of the topic autism and autism spectrum disorders. An historical perspective of the evolution of the disorder opens the issue. Next, comprehensive coverage is given to an article on the definitions, diagnostic criteria, and clinical features of autism spectrum disorders. Other articles in the issue cover the relevant topics like epidemiology, genetic syndromes and genetic testing, early diagnosis and diagnostic evaluation, and neuroimaging and neurochemistry of autism. Authors also present information on tsocial skills for the autistic child, behavioral interventions, and transitioning the autistic child into adulthood, to name a few. This issue should be very well received by pediatricians.