The emergency department (ED) is a complex environment. Its equilibrium, or homeostasis, is critically dependent on the continuous action of feedback processes. For any system to function efficiently, it needs to know the outcomes of specific actions in a consistent, reliable, and expeditious way. Historical attitudes and the unique operating characteristics of the ED have combined to impose sanctions on the proper provision of feedback. The following features have been identified as obstructive to optimal feedback operation: incomplete awareness of the significance of the problem, excessive time and work pressures, case infrequency, deficiencies in specialty follow-up, communication failures, deficient reporting systems for near-misses, error, and adverse events, biases in case review processes, shift changeover times, and shiftwork. The result is that clinicians, nurses, and trainees are working in conditions that are suboptimal for the provision of safe care, as well as for learning and job fulfillment. Good feedback is a necessary condition for well-calibrated performance by individuals, and is integral to effective team function. More needs to be known about outcomes for feedback to work efficiently. The critical role of feedback in other aspects of ED function, such as education and human factors engineering, should be emphasized. The current interest in medical error and evolving attitudes toward a new culture of patient safety provide a unique opportunity to examine feedback and the critical role it plays in ED function.