Approximately 6 % of women with breast cancer are diagnosed before the age of 40, and this disease accounts for more than 40 % of all cancers in women in this age group. Historically, survival rates are worse for younger women when compared to older women; younger age has proven to be an independent predictor of adverse outcome in multivariate analysis. While the basic principles of chemotherapy, radiation, and surgery between younger and older women with breast cancer remain similar, endocrine therapy recommendations for pre- and postmenopausal patients have evolved quite substantially over the past 5 years. When planning local and systemic therapies for young women with breast cancer, the late effects of treatment (i.e., bone health) should be carefully considered. Other factors important to the optimal care of young women with breast cancer include risk of premature menopause, managing the risk of future infertility, impact of therapy on sexual and psychological health, and the implications of inherited cancer syndromes, specifically BRCA1 and BRCA2.