We review the empirical evidence for the validity of the Dissociative Identity Disorder (DID) diagnosis, the vast majority of which has come from research conducted within the last 10 years. After reviewing three different guidelines to establish diagnostic validity, we conclude that considerable converging evidence supports the inclusion of DID in the current Diagnostic and Statistical Manual for Mental Disorders. For instance, DID appears to meet all of the guidelines for inclusion and none of the exclusion guidelines; proposed by Blashfield et al. [Comprehensive Psychiatry 31 (1990) 15-19], and it is one of the few disorders currently supported by taxometric research. However, we also discuss possible problems with the current diagnostic criteria and offer recommendations, based on recent research, for possible revisions to these criteria.