Asperger's Syndrome was first formally defined in 1944 by Hans Asperger, an Austrian pediatrician. Asperger studied social interactions, communication, and behavior in children with different ways of being.

In 1943, he studied a group of children, mostly boys, who had difficulty interacting in socially acceptable ways. The children appeared intrinsic or self-centered — not necessarily selfish, but rather they preferred to keep to themselves. Another common characteristic was that they were not physically adept and were rather uncoordinated. Most experienced no cognitive delays and were, in fact, quite articulate, with a strong command of vocabulary. The children engaged in repetitive physical actions, or were fascinated with nuances of timetables or the mechanics of certain objects such as clocks.

Asperger published his findings in a paper titled “Autistic Psychopathy.” By today's standards, the title is alarming and disrespectful but, in using the word “psychopathy,” Asperger did not intend to describe mentally ill, violent behavior; he was using the clinically acceptable jargon of the day. Asperger's findings were the first documented collection of traits now used to diagnose Asperger's Syndrome.

Unknown to Asperger, a psychiatrist named Leo Kanner was conducting similar research at Johns Hopkins University at about the same time. In 1943, Kanner chose the word “autism” (from the Greek word autos, or “self”) to describe a group of children who shared like but stereotyped personality traits, engaged in solitary actions, and who struggled with expressing communication that was effective, reliable, and understandable. In postwar Austria, Asperger's paper languished while Kanner's research received recognition.