OBJECTIVE: Socioeconomic deprivation is associated with an increased risk of breast cancer mortality. This article summarizes the relationships between socioeconomic status (SES) and breast cancer in white European women compared with racial and ethnic groups in the United States. Furthermore, we examine the association between obesity and breast cancer within socioeconomic disparities. METHODS: Mortality rates were published by the American Cancer Society and the National Cancer Institute Surveillance, Epidemiology, and End Results Program. Obesity data were derived from the National Center for Health Statistics Behavioral Risk Factor Surveillance System. MEDLINE searches were performed using keywords, such as socioeconomic status, poverty, African American, Hispanic, race, and combined with related articles. RESULTS: Socioeconomic deprivation may be responsible for the increased risk of breast cancer mortality in African American and Hispanic patients, as they are more likely than white American patients to be diagnosed with advanced disease. Among white women, social deprivation is related to poor breast cancer prognosis, with increased prevalence rates of high-grade, estrogen receptor (ER)-negative tumors, similar to that of triple-negative breast cancers observed in African American and Hispanic women. Obesity is associated with advanced breast cancer at diagnosis, high tumor proliferation rates, and more triple-negative phenotypes, indicating that it may adversely contribute to prognosis. Conclusions: Most studies show an effect of SES on breast cancer incidence and prognosis. Research should focus on the influence of social deprivation on breast cancer characteristics, such as absence of ER expression, that occurs in African Americans and Hispanics and in white European women with a different genetic background.