Abstract Aims Atherosclerotic cardiovascular disease (ASCVD) risk prediction equations apply to older adults. For this study, the Pathobiologic Determinants of Atherosclerosis in Youth (PDAY) risk score, based on post-mortem measurements of atherosclerosis in 15–34-year olds dying accidentally, was used to predict ASCVD events, specifically myocardial infarction and revascularization, in middle age, from risk measured at ≤40 years of age. Methods and results The Coronary Artery Risk Development in Young Adults Study (CARDIA) collected longitudinal cardiovascular risk data, coronary artery calcium (CAC) scores, and ASCVD data beginning at age 18 and 30 years with 30-year follow-up. Predictive accuracy for ASCVD of the PDAY risk score, calculated at baseline (mean age 24) and at all six CARDIA examinations up until year 15, was examined. We also examined whether the presence of CAC improved model discrimination. The cohort for this study comprised 5004 Black and White men and women, at baseline and 3558 with data at year 15. Each standard deviation increase in PDAY score, at each examination, was significantly associated with future ASCVD. Hazard ratios (per standard deviation) increased from 1.74 to 2.04 from year 0 to year 15. C-statistics ranged from 0.771 to 0.794. Coronary artery calcium measurement at age 33–45 years improved risk prediction only if the score was 0. Cumulative risk exposure over the first 15 years of the CARDIA study also had high-predictive value (c-statistic 0.798, 95% confidence interval 0.762–0.835). Conclusion The PDAY risk score may be used in young adults, prior to age 40 years to predict ASCVD events.