By the year 2030 most patients with breast cancer will be aged 65 years or more and many will be frail. Frailty implies diminished physiologic reserve; contributors include diminished organ function, comorbidities, impaired physical function, and geriatric syndromes. Time-efficient tools for assessing frailty are being developed and, once validated, can be used to identify frail cancer patients and help direct therapy. Screening mammography in frail patients is questionable, and a clinical breast exam is likely to identify breast cancers that warrant intervention. Hormonal therapy may be a reasonable primary therapy in older frail women with hormone receptor–positive lesions. For estrogen receptor– and progesterone receptor–negative lesions, excision of the primary tumor may be adequate. Adjuvant hormonal therapy may be appropriate in frail elders with high-risk hormone receptor–positive breast cancer; chemotherapy is rarely indicated regardless of tumor status. The majority of frail elders with metastases will have hormone receptor–positive breast cancers, and endocrine therapy should be considered; those with receptor-negative tumors may be treated with single-agent chemotherapy or supportive care measures. Oncologists need to acquire the skills to appropriately identify frail elders so they select appropriate therapies that will minimize toxicity and maintain quality of life.