In the past decades the issues of safety and reliability have moved to the centre of both scientific and managerial interest. This is probably connected to an increasing interest in the broader concept of risk which has become a central theme in contemporary social science through the works of Ulrich Beck (1992) and Anthony Giddens (1990). While accidents were traditionally seen as “engineering failure” or “human error”, more recent approaches also emphasize the organizational conditions which determine the safety of organizations. This applies to individual workplace accidents as well as to major industrial disasters. Organizational conditions have been shown to constitute important root causes of major accidents, such as the Chernobyl, Bhopal and Challenger disasters.