Many large, prospective cohort studies originally were established to study common major medical conditions, including heart disease and cancer. These cohorts have provided important health information for decades (eg, the link between smoking and lung cancer). More recently, some of these cohorts also have provided excellent vehicles for addressing important study questions of common rheumatic disorders. An increasing number of important observational studies has been published or are being conducted based on these cohorts; the role of these data sources in rheumatic disease research are likely to grow in the future. This article intends to put these prospective cohort studies together to enhance the understanding of their usefulness in studying rheumatic disorders among investigators and readers. We summarize those cohorts with their published examples of rheumatic disease research.