Optimizing emergency care for the aging population is an important future challenge, as the proportion of older patients at the emergency department (ED) rapidly increases. Older patients, particularly those who are frail, have a high risk of adverse outcomes after an ED visit, such as functional decline, institutionalization, and death. The ED can have a key position in identifying frail older patients who benefit most from comprehensive geriatric care [including delirium preventive measures, early evaluation of after-discharge care, and a comprehensive geriatric assessment (CGA)]. However, performing extensive frailty assessment is not suitable at the ED. Therefore, quick and easy-to-use instruments are needed to identify older patients at risk for adverse outcomes. This narrative review outlines the importance and complexity of frailty assessment at the ED. It aligns the available screening instruments, including clinical judgment as frailty assessment, and summarizes arguments for and against frailty assessment at the ED.