Objective To examine the association of menarche timing with cardiometabolic risk factors into early to mid-adulthood, comparing African American and White women. Study design Analyses included 2583 women (African American = 1333; White = 1250) from the Coronary Artery Risk Development in Young Adults cohort study over 25 years of follow-up (1985-2011). Outcomes included type 2 diabetes, metabolic syndrome, adiposity, glucose, insulin, blood pressure, and blood lipids. Cox models or repeated measures linear regression models estimated the association between age at menarche and the outcomes. Results Each 1-year earlier age at menarche was associated with higher mean body mass index among African American (0.88 ± 0.12 kg/m2, P <.0001) and White (0.89 ± 0.10 kg/m2, P <.0001) women. After body mass index adjustment, each 1-year earlier age at menarche was associated with higher triglycerides (2.26 ± 0.68 mg/dL, P =.001) and glucose (0.34 ± 0.11 mg/dL, P =.002), and greater risk for incident impaired fasting glucose (hazard ratio = 1.13, 95% CI 1.04-1.20) and metabolic syndrome (hazard ratio 1.19, 95% CI 1.11-1.26) among White women only. Conclusions Excess adiposity associated with earlier menarche is sustained through mid-adulthood, and primarily drives higher cardiometabolic risk factor levels. However, White women with earlier menarche had increased risk of a number of insulin-resistance related conditions independent of adiposity. The cardiometabolic impact of earlier menarche was weaker in African American women despite higher average adiposity. Weight maintenance would likely reduce but may not completely eliminate the elevated cardiometabolic risk of earlier menarche.