Background Framingham risk score (FRS) underestimates risk in young adults. Left ventricular mass (LVM) relates to cardiovascular disease (CVD), with unclear value in youth. In a young biracial cohort, we investigate how FRS predicts CVD over 20 years and the incremental value of LVM. We also explore the predictive ability of different cut-points for hypertrophy. Methods We assessed FRS and echocardiography-derived LVM (indexed by body surface area or height2.7) from 3980 African-American and white Coronary Artery Risk Development in Young Adults (CARDIA) participants (1990-1991); and followed over 20 years for a combined endpoint: cardiovascular death; nonfatal myocardial infarction, heart failure, cerebrovascular disease, and peripheral artery disease. We assessed the predictive ability of FRS for CVD and also calibration, discrimination, and net reclassification improvement for adding LVM to FRS. Results Mean age was 30 ± 4 years, 46% males, and 52% white. Event incidence (n = 118) across FRS groups was, respectively, 1.3%, 5.4%, and 23.1% (p < 0.001); and was 1.4%, 1.3%, 3.7%, and 5.4% (p < 0.001) across quartiles of LVM (cut-points 117 g, 144 g, and 176 g). LVM predicted CVD independently of FRS, with the best performance in normal weight participants. Adding LVM to FRS modestly increased discrimination and had a statistically significant reclassification. The 85th percentile (≥ 116 g/m2 for men; ≥ 96 g/m2 for women) showed event prediction more robust than currently recommended cut-points for hypertrophy. Conclusion In a biracial cohort of young adults, FRS and LVM are helpful independent predictors of CVD. LVM can modestly improve discrimination and reclassify participants beyond FRS. Currently recommended cut-points for hypertrophy may be too high for young adults. © 2014 Elsevier Ireland Ltd.