IMPORTANCE The adverse outcomes associated with atrial fibrillation (AF) have been studied in predominantly white cohorts. Racial differences in outcomes associated with AF merit continued investigation. OBJECTIVE To evaluate the race-specific associations of AF with stroke, heart failure, coronary heart disease (CHD), and all-cause mortality in a community-based cohort. DESIGN, SETTING, AND PARTICIPANTS The Atherosclerosis Risk in Communities (ARIC) Study is a prospective, observational cohort. From 1987 through 1989, the ARIC Study enrolled 15 792 men and women and conducted 4 follow-up examinations (2011-2013) with active surveillance for vital status and hospitalizations. Race was determined by self-report and categorized as white, black, or other. MAIN OUTCOMES AND MEASURES Atrial fibrillation (adjudicated using electrocardiograms, hospital discharge codes, and death certificates), stroke, heart failure, CHD, and mortality. RESULTS After exclusions, 15 080 participants (mean [SD] age, 54.2 [5.8] years; 8290 women [55.5%]; 3831 black individuals [25.4%]) were included in this analysis. During a mean (SD) follow-up of 20.6 (6.2) years, there were 2348 cases of incident AF. The incident rates of AF per 1000 person-years were 8.1 (95%CI, 7.7-8.5) in white individuals and 5.8 (95%CI, 5.2-6.3) in black individuals. The rates of stroke, heart failure, CHD, and mortality were higher in black individuals with AF than white individuals with AF. The association of AF with these outcomes, estimated with rate differences (rate of the end point in those with AF minus the rate in those without AF per 1000 person-years), also differed by race. The rate difference for stroke in individuals with AF was 10.2 (95%CI, 6.6-13.9) in white individuals and 21.4 (95%CI, 10.2-32.6) in black individuals. For heart failure and CHD, the rate differences were 1.5- to 2.0-fold higher in black individuals than white individuals. White individuals with AF had a rate difference of 55.9 (95%CI, 48.1-63.7) for mortality compared with black individuals, who had a rate difference of 106.0 (95%CI, 86.0-125.9). CONCLUSIONS AND RELEVANCE In the prospective ARIC Study, the outcome of AF on the rates of stroke, heart failure, CHD, and mortality was considerably larger in black individuals than white individuals. These results indicate the vulnerability and increased risk in black individuals with AF. Continued investigation of racial differences in AF and its related adverse outcomes are essential to identify and mitigate racial disparities in the treatment of AF.