Pervasive health disparities continue to exist among racial/ethnic minority groups, but the factors related to these disparities have not been fully elucidated. We undertook this prospective cohort study to determine the independent contributions of socioeconomic status (SES), health behaviors, and health insurance in explaining racial/ethnic disparities in mortality and health declines. Our study period was 1992-1998, and our study population consists of a US nationally representative sample of 6286 non-Hispanic whites (W), 1391 non-Hispanic blacks (B), 405 Hispanics interviewed in English (H/E), and 318 Hispanics interviewed in Spanish (H/S), ages 51-61 in 1992 in the Health and Retirement Study. The main outcome measures were death; major decline in self-reported overall health (SROH); and combined outcome of death or major decline in SROH. Crude mortality rates over the 6-year study period for W, B, H/E and H/S were 5.8%, 10.6%, 5.8%, and 4.4%, respectively. Rates of major decline in SROH were 14.6%, 23.2%, 22.1% and 39.4%, for W, B, H/E and H/S, respectively. Higher mortality rates for B versus W were mostly explained by worse baseline health. For major decline in SROH, education, income, and net worth independently explained more of the disparities for all three minority groups as compared to health behaviors and insurance, reducing the effect for B and H/E to non-significance, while leaving a significant elevated odds ratio for H/S. Without addressing the as-yet undetermined and pernicious effects of lower SES, public health initiatives that promote changing individual health behaviors and increasing rates of insurance coverage among blacks and Hispanics will not eliminate racial/ethnic health disparities.