Despite the fact that the United States boasts one of the most advanced health care systems in the world, this system is highly "unreliable" and fraught with error. This article is an introduction to the concept of "reliability" in emergency medicine. It suggests ways in which the health care system could promote increased reliability of operations and processes in the emergency department by using reliability principles and tools that have proven successful in other high-risk settings. Through comparisons to aviation and nuclear power, this article illustrates the differences in culture between emergency medicine and other high-risk organizations and points to the qualities that promote reliability. Finally, a specific model for reliability in the emergency department, operations, and clinical processes is proposed.