The fibromyalgia syndrome (FM) workshop at OMERACT 8 continued the work initiated in the first FM workshop at OMERACT 7 in 2004. The principal objectives were to work toward consensus on core domains for assessment in FM studies, evaluate the performance quality of outcome measures used in a review of recent trials in FM, and discuss the research agenda of the FM working group. An initiative to include the patient perspective on identification and prioritization of domains, consisting of focus groups and a patient Delphi exercise, was completed prior to OMERACT 8. Patient-identified domains were, for the most part, similar to those identified by clinician-investigators in terms of symptoms and relative importance. However, patients identified certain domains, such as stiffness, that were not included by physicians, and emphasized the importance of domains such as dyscognition and impaired motivation. Many of the principal domains agreed upon by the clinician-investigators, patients, and OMERACT participants, including pain, fatigue, sleep, mood, and global measures, have been used in clinical trials and performed well when viewed through the OMERACT filter. The research agenda items reviewed and approved for continued study included development of objective "biomarkers" in FM, development of a responder index for FM, and coordination with the WHO's International Classification of Functioning Disability and Health (ICF) Research Branch and the US National Institutes of Health's Patient Reported Outcome Measures Information System network (PROMIS) to develop improved measures of function, quality of life, and participation. The OMERACT process has provided a framework for identification of key domains to be assessed and a path toward validation and standardization of outcome measures for clinical trials in FM.