Breast cancer among young women is rare and often associated with high-risk features. Age alone has been shown to be an independent risk factor for recurrence, although the biologic explanation for the increased risk among younger women remains unknown. Due to the higher risk of recurrence and otherwise typically good health of young women with breast cancer, one must carefully consider both the maximally effective approach to treatment and the potential long-term consequences of therapy. This manuscript focuses on the clinical decisions that we confront when considering systemic therapy for young women with early-stage breast cancer and the evolving data to guide the care of these patients.