The purpose of this chapter is to elucidate the key issues regarding the classification of eating disorders. To this end, a review of nosological research in the area of eating disorders is presented, with a particular focus on empirically based techniques such as taxometric analysis, latent class analysis, and factor mixture modeling. This is followed by a section outlining areas of overlap between the current Diagnostic and Statistical Manual of Mental Disorders–Fifth Edition (DSM-5) eating disorder categories and their symptoms. Next, eating disorder classification models that are alternatives to the DSM-5 are described and critically examined in light of available empirical data. Finally, areas of controversy and considerations for change in next version of the DSM (i.e., the applicability of DSM criteria to minority groups, children, and males; the question of whether clinical categories should be differentiated from research categories) are discussed.