Many key concepts under-girding organizational effectiveness are captured in the theory of high reli ability (Weick and Roberts 1993, Weick and Sutcliffe 2001, DeGrosky and other articles in this issue). Simplistically, a High Reliability Figure 1. The Principles of High Reliability Organizing. Organization (HRO) is one that consistently produces the results in a dynamic, often unpredictable environment in which the conse quences of errors are catastrophic. Accordingly, the error rate of an HRO is substantially lower than other businesses in the same field. Traditionally, there have been two main approaches to reliability. One seeks to anticipate events that must not happen, identify all possible precursor events or conditions, and then create a set of procedures nec essary to guard against the unde sired outcome. Anticipation focuses on picking up weak signals before they can incubate into larger, more catastrophic events. The second approach to high reli ability considers anticipation. In this view, reliability is finding ways to cope with and contain undesired events as they occur—and before their effects escalate. Over the past decade, research ers have realized that the most successful organizations use both strategies.