The term autism was first introduced in 1908. The famous Swiss psychiatrist Eugen Bleuler used the term autism to describe the very aloof and withdrawn condition of some patients with what he called schizophrenia. Leo Kanner (1943), when describing eleven children with “an autistic disturbance of affective contact”, clearly had Bleuler’s thoughts in mind. Likewise Hans Asperger (1944) called the atypical boys in his study “autistic psychopaths”, hereby also alluding to some resemblance with schizophrenia. Despite the fact that “autistic aloofness” does not by far cover the complexity of the pervasive developmental disorder described nowadays as “autism spectrum disorder”, the term has become the common way to describe the large range of individuals with a syndrome characterized by impairments of the development of social and communicative reciprocity and a rigid and restricted repertoire of interests and behaviours. In this chapter a historical overview of the development of a concept in psychopathology will be presented. It may be interesting to note, before entering into the matter, that Bleuler believed that there was a continuum between psychiatric disorders and normality. This is very much in line with the current concept of a broad autism spectrum ranging from severe cases to well-adapted individuals with autistic features bordering what Simon Baron-Cohen would call an autistic condition including 5 % of the population.