A review of anesthesia safety and errors, this article provides an overview of the definitions, issues, and challenges facing the field. The authors discuss the characteristics of systems predisposing to accidents, including what they describe as two key elements: The first is a complexity of interactions that exists in systems and the second is the absence of “tight coupling,” which represents interdependence among parts of a system. The discussion continues by contrasting incidents and accidents and the cognitive processes involved in trying to balance time and production pressures within a larger system. The authors recommend greater emphasis on detecting simple incidents, using simulators to promote education and training, detailing backup equipment, and disseminating effective protocols for particular incidents.