Breast cancer is the most common noncutaneous malignancy and the second most lethal form of cancer among women in the United States. Mortality from breast cancer has declined since the late 1980s, but this decline has been steeper among white women compared with black women. As a result, the black:white mortality rate ratio has increased over the last two decades. Other ethnic minorities also suffer from disproportionately high breast cancer mortality rates. This review discusses the causes of racial and ethnic disparities in breast cancer mortality and describes the most common approaches to reducing these disparities. The literature suggests that outcome disparities are related to patient-, provider-, and health system-level factors. Lack of insurance, fear of testing, delay in seeking care, and unfavorable tumor characteristics all contribute to disparities at the patient level. At the provider level, insufficient screening, poor follow-up of abnormal screening tests, and nonadherence to guideline-based treatments add to outcome disparities. High copayment requirements, lack of a usual source of care, fragmentation of care, and uneven distribution of screening and treatment resources exacerbate disparities at the health system level. Although pilot programs have increased breast cancer screening among select populations, persistent disparities in mortality suggest that changes are needed at the policy level to address the root causes of these disparities.