Breast cancer is a disease that is associated with aging, with almost one-half of all new breast cancer cases diagnosed annually in the United States occurring in women ages 65 and older. Recent data suggest that although breast cancer outcomes in younger women have shown substantial improvement as a result of advances in treatment and screening, the benefits in older women have been less pronounced. Although older patients have been underrepresented in cancer clinical trials, there is an emerging body of literature to help guide treatment decisions. For early-stage breast cancer, the discussion regarding treatment options involves balancing the reduction in risk of recurrence gained by specific therapies with the potential for increased treatment-related toxicity, potentially exacerbated by physiological decline or comorbidities that often co-exist in the older population. A key component of care is the recognition that chronologic age alone cannot guide the management of an older patient with breast cancer. Rather, treatment decisions must also take into account a patient's functional status, estimated life expectancy, the risks and benefits of the therapy, potential barriers to treatment, and patient preference. This article reviews the available evidence for therapeutic management of early-stage breast cancer in older patients, and highlights data from the geriatric oncology literature that provide a basis on which to facilitate evidence-based treatment.