This article revisits the persistent problem of crowding in US hospital emergency departments (EDs). It begins with a brief review of origins of this problem, terms used to refer to ED crowding, proposed definitions and measures of crowding, and causal factors. The article then summarizes recent studies that document adverse moral consequences of ED crowding, including poorer patient outcomes; increased medical errors; compromises in patient physical privacy, confidentiality, and communication; and provider moral distress. It describes several organizational strategies implemented to relieve crowding and implications of ED crowding for individual practitioners. The article concludes that ED crowding remains a morally significant problem and calls on emergency physicians, ED and hospital leaders, emergency medicine professional associations, and policymakers to collaborate on solutions.