A continually evolving discipline, Human Reliability Assessment (HRA) has elements of controversy from the definition of terms to the application of appropriate methods for the representation of human failure probability. The idea that human error is a random event is falling out of favour and the concept that humans can be set up to fail or succeed depending on context is gaining credibility. Provides an in-depth exploration of current theories, demonstrates how to model, change, and apply new approaches to a number of different high-risk industries. Also covers data and data sources, choice of methods, training of individuals, use of simulators for HRA purposes, and the relationship between psychology, human factors, accident analyses, and human reliability. And includes a number of accident studies that illustrate the key roles of operators and managers in accident mitigation and control.