Due to its superior nutritional composition and non-nutritional immunologic components, breast milk is the biological normative standard for infant feeding. Additionally, breastfeeding has extensive maternal-infant dyad health and bonding benefits. Increasing the number of infants who receive breast milk within the first year of life is a worldwide health goal that the United States (U.S.) and most other countries seek to promote. While the U.S. is falling short of national and international guidance on breastfeeding goals, the overall rates mask significant racial and ethnic disparities. Black American women have the lowest rates of exclusive breast milk feeding compared with other racial and ethnic groups. This study aimed to 1) Examine whether hospital variation in nursing resources, including patients-per-nurse staffing ratios and the nurse work environment during labor and birth, is associated with variation in exclusive breast milk feeding rates, 2a) Determine whether exclusive breast milk feeding rates are lower in predominantly Black-serving hospitals, 2b) Examine whether better nursing resources diminish racial disparities in hospital-level exclusive breast milk feeding rates. These aims were fulfilled using cross-sectional secondary data from nurses, hospitals, and patients to achieve the study aims. Two cross-sections of nurse survey data from different periods fulfilled Aim 1. The first nurse data source was derived from the RN4CAST-US survey from 2015 to 2016, representing nurses in hospitals from California (CA), Florida (FL), and New Jersey (NJ). The second cross-section of nurse survey data was collected between December 2019 and February 2020 from New York (NY) and Illinois (IL) nurses. Both cross-sections (five states) were used to analyze Aim 1. Due to limited access to NY and IL corresponding patient-level administrative data, only nurse survey data from the RN4CAST-US (CA, FL, NJ) were used in Aim 2 analyses. To examine Aim 1, these nurse data were merged into multiple other sources using unique identifiers, including (1) the 2015-2016 and 2019-2020 American Hospital Association (AHA) Annual Survey data, (2) Baby Friendly Hospital Designation, and (3) The Joint Commission PC-05 Exclusive Breast Milk Feeding hospital-level data. The findings of this study underscore the crucial role of nurse work environments in promoting higher exclusive breast milk feeding rates. Additionally, the proportion of Black women giving birth in a hospital was found to be significantly associated with a decline in hospitals’ exclusive breast milk feeding rates. Notably, the nurse work environment, nurse staffing, and the proportion of Black women giving birth in the hospital remained significant even in the fully adjusted regression model, further highlighting the robustness of these associations. Hospitals should improve nurses’ work environments and staffing to support breastfeeding outcomes. Patient feedback on the experience of Black women giving birth in hospitals is needed to guide hospital administrators on how to improve breastfeeding outcomes.