Pregnancy-associated breast cancer is defined as invasive breast cancer diagnosed during gestation, within 1 year postpartum, or during lactation. Of particular interest is the treatment of invasive breast cancer during gestation; standard treatment protocols must take into account the health of the fetus. This article reviews the literature and emerging data regarding the treatment of pregnancy-associated breast cancer. Existing staging and treatment practices need slight modification in the setting of pregnancy. The timing of surgery and the administration of cytotoxic chemotherapy must take into account age of gestation, but these modalities are safe in pregnancy.