This thesis is an empirical investigation of the fifth edition of the American diagnose manual; Diagnostic and Statistical Manual of Mental Disorders (DSM-5). More specifically it is about the decision to rule out the diagnosis Asperger syndrome (AS), and rather merge it into Autism Spectrum Disorder (ASD). This research aims to explore the controversy surrounding the DSM-5 revision through trending debates about AS, and in comparison to the International Classification of Diseases (ICD). The book “Asperger syndrome” edited by Volkmar, Klin and Sparrow (2000) deploys the debate about AS in totality up the year 2000. Most importantly, it describes a gap between available research and clinical knowledge. Researchers have long claimed that AS is an unresolved issue, and that its validity cannot be accounted for, while clinicians tend to use the term excessively and see it as helpful and a necessity, and hence diagnosing an increasing number of individuals with AS. It is a gap between the DSM-5 Task Force and the public; is it possible for developers on the Task Force that has little or no clinical experience to make such decisions, when the majority of the manuals users see the necessity of the diagnosis? The gap between the DSM-5 and its opponents is obviously great. Why is it that the DSM-5 has such a contrasting view? Interestingly, the removal of AS emerges at the same time that research implicates a factual neurobiological and genetic qualitative difference between autism and AS. In addition, there are important aspects of the diagnosis not considered before this removal, such as the social utility of the diagnosis and the practice associated with AS – and equally important, the clinical practice of AS. This raises concerns about the appropriateness of the removal; especially about the encompassment of the ASD criteria’s in that they would exclude substantial individuals in need of a diagnosis. Thus, what need to be explored are everyday practices and routines associated with Asperger syndrome. The DSM-5 Work Group, however, may not have recognized the importance of the AS diagnosis beyond the clinical labelling – culture and practice – and therefore come to characterize it as an excess diagnosis with no utility. In order to go beyond this narrow description of AS, this will be analysed through STS theory about expertise, knowledge, models of science; the deficit model and the participatory model, and the method of ‘praxiography’. This enables an analysis of the actors enrolled in the controversy of the DSM-5 development, and hence the actors excluded. More importantly, it facilitates a discussion about how some forms of knowledge are considered important, while other forms of knowledge are denoted – and consequently, enables an analysis of how new actors and forms of knowledge are introduced to the controversy and enacted in practice. Key words: classification, included/excluded expertise, framing, enactment, social identity, employment, financial conflicts of interests, and encompassment.