Results indicated significant stability in categorization of pubertal timing based on grade at first menarche. However, approximately 10 percent of the girls changed pubertal timing category over the 4-year study period. At least 15 percent of the girls categorized as early maturers were recategorized. All three ethnic groups included in the study showed similar trends in recategorization. The findings underscore the importance of multimethod approaches to the measurement of puberty. The authors advise that individual researchers should decide for themselves whether menarcheal self-report is sufficiently stable as a measure of pubertal timing for their research purposes. Participants were 1,976 girls in fourth through ninth grades who participated in the McKnight Longitudinal Risk Factor Study. Participants completed the McKnight Risk Factor Survey that included questions regarding ethnicity and self-reported grade at first menarche. Participants completed the questionnaire at baseline and then annually for up to 3 years. Data were analyzed using Kappa statistics and the McNemar tests. Tables, note, references