This issue of Child and Adolescent Psychiatric Clinics, guest edited by Drs. Robert Wisner-Carlson, Thomas Flis, Scott Pekrul and Robert Schloesser, will cover key topics of importance surrounding Autism Spectrum Disorders Across the Lifespan. This issue is Part I of II and one of four selected each year by our series Consulting Editor, Dr. Harsh Trivedi. Topics discussed in this issue include but are not limited to: Diagnosis, Developmental Changes, Social Skills Training, Transition through Adulthood, Intersection with Eating Disorders, Legal Issues and planning, Education, and Vocational and Prevocational issues, among other topics.