Early onset of menarche impacts the future health of adolescent girls. We examined if soy is related to age at onset of menarche (AOM) in a population with a high and wide range of soy intake . We conducted a cross-sectional study on 339 girls ages 12-18 years in selected middle and high schools in California and Michigan using a web-based physical development and dietary intake (DI) questionnaire. Soy consumption (categorized as total soy , meat analogs, tofu/ traditional soy , and soy beverages ) was estimated from the DI while AOM was self-reported. Data analyses included descriptive statistics, Cox proportional hazard ratios, and Poisson regression with adjustment for confounders.Mean (SD) intakes were: total soy ,12.9 (14.4) svg/wk; meat analogs, 7.0 (8.9) svg/wk; tofu/traditional soy , 2.1 (3.8) svg/wk; soy beverages, 3.8 (6.3) svg/wk. Mean AOM for those who reached menarche was 12.5 (1.4) y. Consumption of total soy and the 3 types of soy foods were not significantly associated with AOM neither with the odds for early- or late-AOM. Adjustment for demographic and dietary factors did not change the results. Soy intake is not associated with AOM in a population of adolescents who have a wide range and relatively higher intake of soy than the general US population. Our finding suggests that the increasing popularity of soy in the US may not be associated with the declining trend in menarcheal age .