Behavioural safety programmes seek to turn ‘unsafe cultures' into ‘safe cultures'. Although safety culture improvement campaigns often successfully reduce accident rates, their effectiveness fades over time. with persistent rump of accidents and incidents remaining. It will be suggested that this is because the steps taken to improve occupational health and safety culture differ from those necessary to improve systems safety culture. Behavioural safety programmes are unsuccessful due to an over-simplistic application of social science theories by we engineers. A more sophisticated cultural model will be offered to help improve future campaigns and help understand why systems safety needs contributions from multiple disciplines. Finally risk-free cultures will be contrasted with strategies to adapt an existing project culture.