Background: Neighborhood socioeconomic status (nSES) has been found to be associated with breast cancer risk. It remains unclear whether this association applies across racial/ethnic groups independent of individual-level factors and is attributable to other neighborhood characteristics.Methods: We examined the independent and joint associations of education and nSES with odds of breast cancer. Residential addresses were geocoded for 2,838 cases and 3,117 controls and linked to nSES and social and built environment characteristics. We estimated ORs and 95% confidence intervals (CI) using multilevel logistic regression controlling for individual-level breast cancer risk factors and assessed the extent to which nSES associations were due to neighborhood characteristics.Results: Women living in the highest versus lowest nSES quintile had a nearly 2-fold greater odds of breast cancer, with elevated odds (adjusted ORs, 95% CI) for non-Hispanic whites (NHWs; 2.27; 1.45-3.56), African Americans (1.74; 1.07-2.83), U.S.-born Hispanics (1.82; 1.19-2.79), and foreign-born Hispanics (1.83; 1.06-3.17). Considering education and nSES jointly, ORs were increased for low education/high nSES NHWs (1.83; 1.14-2.95), high education/high nSES NHWs (1.64; 1.06-2.54), and high education/high nSES foreign-born Hispanics (2.17; 1.52-3.09) relative to their race/ethnicity/nativity-specific low education/low nSES counterparts. Adjustment for urban and mixed-land use characteristics attenuated the nSES associations for most racial/ethnic/nativity groups except NHWs.Conclusions: Our study provides empirical evidence for a role of neighborhood environments in breast cancer risk, specifically social and built environment attributes.Impact: Considering the role of neighborhood characteristics among diverse populations may offer insights to understand racial/ethnic disparities in breast cancer risk. Cancer Epidemiol Biomarkers Prev; 26(4); 541-52. ©2017 AACR.