Fibromyalgia is a disorder characterized by chronic widespread pain in the presence of widespread tenderness, and multiple somatic symptoms. Since the publication of the American College of Rheumatology (ACR) 1990 classification criteria for fibromyalgia, research has proliferated and, in a relatively short period, investigators have begun to unravel the etiology and long-term impact of this complex condition. Although the ACR 1990 criteria have been central to fibromyalgia research during the past two decades, a number of practical and philosophical objections have been raised in relation to them. Principally these objections have centered on the use (or lack thereof) of the tender point examination, the lack of consideration of associated symptoms, and the observation that fibromyalgia might represent the extreme end of a pain continuum. In developing the ACR 2010 criteria, experts have sought to address these issues and to simplify clinical diagnosis. An implicit aim was to facilitate more rigorous study of etiology. The purpose of this Review is to summarize research to date that has described the epidemiology, pathology and clinical course of fibromyalgia, and to assess the probable impact of the ACR 2010 criteria on future research efforts.