Breast cancer is the second most common cancer among women in the United States, after skin cancer, and the second-leading cause of cancer death, after lung cancer. Yet breast cancer mortality rates have been declining, most probably the result of early detection and better treatment. Advances in hormone therapy and discoveries of antibody treatments have markedly improved the outcome for breast cancer patients, along with the development of genetic tests on tumor tissue to determine which patients will best benefit from chemotherapy. While progress is being made, some debates seem never to fade. There continue to be disagreements about the age at which women should begin mammography screening, how to treat the increasing number of “zero stage” breast cancers that screening detects and the extent to which environmental pollutants cause breast cancer. In addition, disparities in treatment and racial outcomes continue to be documented.