The timing of natural menopause has implications for several health endpoints; in particular, it is a risk factor for breast cancer. The authors investigated factors influencing the timing of natural menopause among 95,704 women with a mean age of 59.7 years (10th-90th percentile range, 47.0-71.0) in five racial/ethnic groups in the Multiethnic Cohort Study, including non-Latina Whites, Japanese Americans, African Americans, Native Hawai'ians, and Lat- inas. The authors investigated whether race/ethnicity and several lifestyle and reproductive characteristics were associated with the timing of natural menopause. Race/ethnicity was a significant independent predictor of the timing of natural menopause. Other factors, including smoking, age at menarche, parity, and body mass index, did not significantly alter the race/ethnicity-specific hazard ratios. Relative to non-Latina Whites, natural menopause occurred earlier among Latinas (US-born Latinas: hazard ratio (HR) ¼ 1.10, 95% confidence interval (CI): 1.07, 1.14; non-US-born Latinas: HR ¼ 1.25, 95% CI: 1.21, 1.30) and later among Japanese Americans (HR ¼ 0.93, 95% CI: 0.90, 0.95). These results support the hypothesis that the timing of natural menopause is driven by a combination of genetic, reproductive, and lifestyle factors. cohort studies; continental population groups; epidemiologic factors; menopause