A holistic safety and health approach is necessary for a company to succeed in achieving zero harm. Potential systemic failures are highlighted that could exist within organizations, which create the 'error traps' where accidents become inevitable. Safety and health leadership strategies and the interdependencies between leadership components and health and safety systems are described to understand 'cause and effect'. Human factors and human error in health and safety, as well as the application of behavioural safety theory and methods, help to look at people in context, both within and outside the workplace.