The Research Domain Criteria (RDoC) project was initiated by the National Institute of Mental Health (NIMH) in early 2009 as the implementation of Goal 1.4 of its just-issued strategic plan. In keeping with the NIMH mission, to "transform the understanding and treatment of mental illnesses through basic and clinical research," RDoC was explicitly conceived as a research-related initiative. The statement of the relevant goal in the strategic plan reads: "Develop, for research purposes, new ways of classifying mental disorders based on dimensions of observable behavior and neurobiological measures." Due to the novel approach that RDoC takes to conceptualizing and studying mental disorders, it has received widespread attention, well beyond the borders of the immediate research community. This review discusses the rationale for the experimental framework that RDoC has adopted, and its implications for the nosology of mental disorders in the future.