In May 2013 the APA will release DSM-5, which will restructure the diagnostic classification for autism spectrum disorders (ASDs) into a single category. The proposed changes in DSM-5 aim to better reflect the current state of research by consistently identifying the core features in social/communication and restrictive and repetitive behaviors that are specific to ASDs. This review describes the empirical and theoretical bases of research in the nosology of ASDs, given the impending shift in DSM-5 diagnostic criteria. General issues in diagnosis and prevalence are described, with differences between DSM-IV and DSM-5 highlighted. To address concerns about the application of the proposed DSM-5 criteria, the current literature assessing the sensitivity and specificity of the proposed DSM-5 criteria is reviewed. Last, we discuss the implications of the changes in DSM-5 for the treatment of ASDs and recommend areas for future research.