The investigators are conducting a longitudinal cohort study of young women with breast cancer. The investigators identify women age 40 and younger with newly-diagnosed breast cancer from academic and community healthcare institutions. After women consent to the study, they fill-out surveys and give blood samples, and the investigators collect tissue from their breast cancer tumor after it is removed. Women are surveyed every 6 months for the first 3 years after diagnosis, then yearly thereafter for an additional 7 years (for a total follow-up of at least 10 years following diagnosis). The study investigates short and long-term disease and treatment issues, tumor biology and the relationship to patient outcomes, and psychosocial concerns at baseline and in follow-up among a cohort of young women who are newly-diagnosed with breast cancer.