Schnabel et al validated the performance of a recently published Framingham Heart Study–derived risk algorithm for incident atrial fibrillation (AF) modified for 5-year incidence in 2 geographically and ethnically diverse cohorts: AGES (Age, Gene/Environment Susceptibility-Reykjavik Study [n = 4238]) and CHS (Cardiovascular Health Study [n = 5410, of whom 874 were African Americans]). The risk algorithm included age, sex, body mass index, systolic blood pressure, electrocardiographic PR-interval, hypertension treatment, and heart failure. The strongest risk factors were age and heart failure. The relative risks for incident AF associated with risk factors were comparable across cohorts and racial groups. After recalibration for baseline incidence and risk factor distribution, the Framingham algorithm performed reasonably well in all samples. Risk of incident AF in community-dwelling whites and African Americans can be assessed reliably by routinely available and potentially modifiable clinical variables.