The temporomandibular disorder (TMD) research community has been using the Research Diagnostic Criteria for TMD (RDC/TMD) since 1992, and its original developers have much to be proud of because of their widespread acceptance.1 They have accomplished their initial goal of getting researchers to use some common language in classifying TMD patients, and by forming the International Consortium for RDC/TMD-Based Research they have enabled clinical researchers around the world to apply this system in their native languages. However, even from the very beginning there have been some doubts and concerns about the validity as well as the utility of this taxonomic system. During the past 16 years, other classification systems for TMD such as the one proposed by the American Academy of Orofacial Pain (AAOP),2 as well as the broader headache classification system of the International Headache Society (IHS),3 have coexisted with the RDC/TMD, but a direct confrontation was avoided by describing the former two as clinical classifications while the latter was intended for research purposes.