This Funding Opportunity Announcement (FOA) issued by the Office of Research on Women's Health (ORWH) and co-sponsoring Institutes and Centers (ICs) of the National Institutes of Health (NIH) encourages investigator(s)-initiated applications that propose to examine the etiology, diagnosis, pathophysiology, and treatment of chronic fatigue syndrome (CFS), sometimes referred to as myalgic encephalomyelitis (ME), in diverse groups and across the lifespan. Applications that address gaps in the understanding of the environmental and biological risk factors, the determinants of heterogeneity among patient populations, the common mechanisms influencing the multiple body systems that are affected in ME/CFS are encouraged. The NIH is particularly interested in funding interdisciplinary research that will enhance our knowledge of the disease process and provide evidence based solutions to improve the diagnosis, treatment, and quality of life of all persons with ME/CFS. This interdisciplinary research may include the building of scientific teams to study and develop biomarkers, innovative treatment modalities, and/or the modifiable risk and protective processes specifically targeted by preventive and/or treatment interventions. Applications submitted under this mechanism should be exploratory and novel, and should break new ground or extend previous discoveries toward new directions or applications.