The Asperger-Syndrom is a pervasive developmental disorder, characterized by impairments in primarily social and communicative competence, empathy, associated with motor awkwardness and/or clumsiness and highly circumscribed interests. The diagnostic criteria and the diagnostic methods are in detail exemplified. While the validity of autism (Kanner-syndrom) has been shown through multiple different levels of evidence, the validity of Asperger-Syndrom is still unestablished. The few literature is extremely difficult to summarize (Volkmar u. Klin 2000), given that a range of important methodological issues render comparability of findings across studies virtually impossible: these include differences in definition and circularity in definition relative to validating measures. In terms of causes of Asperger-Syndrom the following factors are discussed: genetic reasons, neurobiological disturbances and neuropsychological deficits.