Several studies have shown that there is information loss during interruptions, and that multitasking creates higher memory load, both of which contribute to medical error. Nowhere is this more critical than in the emergency department (ED), where the emphasis of clinical decision is on the timely evaluation and stabilization of patients. This paper reports on the nature of multitasking and shift change and its implications for patient safety in an adult ED, using the methods of ethnographic observation and interviews. Data were analyzed using grounded theory to study cognition in the context of the work environment. Analysis revealed that interruptions within the ED were prevalent and diverse in nature. On average, there was an interruption every 9 and 14 min for the attending physicians and the residents, respectively. In addition, the workflow analysis showed gaps in information flow due to multitasking and shift changes. Transfer of information began at the point of hand-offs/shift changes and continued through various other activities, such as documentation, consultation, teaching activities and utilization of computer resources. The results show that the nature of the communication process in the ED is complex and cognitively taxing for the clinicians, which can compromise patient safety. The need to tailor existing generic electronic tools to support adaptive processes like multitasking and handoffs in a time-constrained environment is discussed.