abstract: Leo Kanner first described autism in his 1943 article in Nervous Child titled "Autistic Disturbances of Affective Contact". Throughout, he describes the eleven children with autism in exacting detail. In the closing paragraphs, the parents of autistic children are described as emotionally cold. Yet, he concludes that the condition as he described it was innate. Since its publication, his observations about parents have been a source of controversy surrounding the original definition of autism. Thus far, histories about autism have pointed to descriptions of parents of autistic children with the claim that Kanner abstained from assigning them causal significance. Understanding the theoretical context in which Kanner's practice was embedded is essential to sorting out how he could have held such seemingly contrary views simultaneously. This thesis illustrates that Kanner held an explicitly descriptive frame of reference toward his eleven child patients, their parents, and autism. Adolf Meyer, his mentor at Johns Hopkins, trained him to make detailed life-charts under a clinical framework called psychobiology. By understanding that Kanner was a psychobiologist by training, I revisit the original definition of autism as a category of mental disorder and restate its terms. This history illuminates the theoretical context of autism's discovery and has important implications for the first definition of autism amidst shifting theories of childhood mental disorders and the place of the natural sciences in defining them. / Dissertation/Thesis / Masters Thesis Biology 2014