The Atherosclerosis Risk in Communities (ARIC) Study was initiated in 1985 with two components: community-based surveillance and a prospective cohort study. The community surveillance aimed to monitor trends in hospitalized myocardial infarction (MI), fatal coronary heart disease (CHD) in four U.S. communities: Forsyth County, NC; Jackson, MS; suburbs of Minneapolis, MN; and Washington County, MD. Surveillance for hospitalized heart failure (HF) events was added in 2005. The communities were selected to provide data across four (4) geographic locations with a range of mortality rates, in urban, suburban, and rural settings. The cohort study aimed to investigate the risk factors for and natural history of atherosclerosis and development of clinical atherosclerosis in middle-aged white or African American adults from the same communities. The study recruited in 15,792 white or African American participants initially aged 45-64 years and selected participants received triennial clinical exams over the first ten years of the study (1987-1989, 1990-1992, 1993-1995, and 1996-1998). The clinical exam in 2011-13 was conducted on over 6,500 participants 69-89 years with a focus on characterizing heart failure stages in community-dwelling participants and enabling identification of genetic and environmental factors leading to ventricular dysfunction and vascular stiffness. These data provided the basis for several ancillary studies covering a breadth of topics. The clinical exam in 2018-19 on almost 3,600 participants 75 years and older supported exam components from 12 NIH grant-funded ancillary studies on topics including progression of Heart Failure with preserved Ejection Fraction (HFpEF), coronary artery calcification, atrial fibrillation burden detected by novel continuous ECG monitoring technology, diabetes, dementia, brain amyloid deposition, and changes in arterial stiffness and cognition. Participation of the surviving cohort was 91, 82, 74, 65, and 50% at each of the respective follow-up examinations. Blood samples have been assayed for putative biochemical risk factors and stored for case-control studies. DNA has been extracted and lymphocytes cryopreserved (for possible immortalization) for study of candidate genes, genome-wide scanning, expression, and other –omics investigations. Since baseline, cohort members have also been contacted every 12 months (and every 6 months since 2012) to obtain information on vital status, current residence, major illness or injury, and hospitalizations occurring between contacts to identify clinical cardiovascular disease (CVD) events. Cohort contact was 78% at the last completed follow-up period. Findings have been presented in over 2,600 publications as of 2021.