The ubiquity of computerized hospital information systems, and of inexpensive computing power, has led to an unprecedented opportunity to use electronic data for quality improvement projects and for research. Although hospitals and emergency departments vary widely in their degree of integration of information technology into clinical operations, most have computer systems that manage emergency department registration, admission-discharge-transfer information, billing, and laboratory and radiology data. These systems are designed for specific tasks, but contain a wealth of detail that can be used to educate staff and improve the quality of care emergency physicians offer their patients. In this article, the authors describe five such projects that they have performed and use these examples as a basis for discussion of some of the methods and logistical challenges of undertaking such projects.