This issue of Psychiatric Clinics, guest edited by Drs. Robert Wisner-Carlson, Thomas Flis, Scott Pekrul, and Robert Schloesser will discuss a number of important topics addressing Autism Disorders Across the lifespan. This issue is one of four each year selected by our series consulting editor, Dr. Harsh Trivedi of Sheppard Pratt Health System. Part II of this issue will be publishing subsequently. Articles in this issue include: Diagnosis of Autism Spectrum Disorder Across the Lifespan; The Role of Diagnostic Instruments in Dual and Differential Diagnosis in Autism Spectrum Disorder Across the Lifespan; Current Approaches to the Pharmacologic Treatment of Core Symptoms Across the Lifespan of Autism Spectrum Disorder; Autism and Education; The Transition to Adulthood for Young People with Autism Spectrum Disorder; Social Skills Training in Autism Spectrum Disorder Across the Lifespan; Competitive Integrated Employment for Youth and Adults with Autism: Findings from a Scoping Review; Transitioning from Adolescence to Adulthood with Autism Spectrum Disorder: An Overview of Planning and Legal Issues; Intersection of Eating Disorders and the Female Profile of Autism; and Obsessive–Compulsive Disorder in Autism Spectrum Disorder Across the Lifespan.