Background:Early life is critical in mammary carcinogenesis and, thus, prevention efforts are increasingly shifting focus to examining youth.Obesity and chronic stress exposures (adverse life events, low socioeconomic status) are independently associated with early pubertal development that increases subsequent breast cancer risk.Specific Aims:In a multiethnic cohort of 443 girls, aged 6-7 at baseline, and followed for 2 years to date: 1. Determine the strength of the associations among chronic stress, visceral fat, early breast development (thelarche) and menarche. 2. Address unresolved questions about potential mediators of the link among chronic stress, visceral adiposity and the timing of thelarche and menarche.Methods:The proposed study builds on an established prospective epidemiological observational study of environmental determinants of puberty and breast cancer risk (n=443) (PI: Dr. Larry Kushi, Kaiser Permanente Northern California), which is a part of the NIH-funded Bay Area Breast Cancer and the Environment Research Center (PI: Dr. Robert Hiatt). Participants are recruited concurrently at sites in Cincinnati and New York, providing an opportunity to expand analyses across sites (N greater than 1200).Implications:The proposed study is poised to advance the field of breast cancer prevention by being the first to longitudinally examine associations among stress, obesity and pubertal timing. The findings of this study will help inform interventions targeting modifiable factors such as physical activity and diet in order to prevent obesity and delay puberty. Such interventions constitute a promising strategy for primary prevention of breast cancer.