The Safety Culture Working Group has produced “A position paper for assessing and managing safety culture”. It provides high-level guidance on the assessment and improvement of safety culture for organisations that design, build, assure and operate complex safety-critical systems. It synthesises recognised good practice and can act as a benchmark and guidance. It (a) exemplifies how safety culture manifests itself, (b) provides guidance on good practice that organisations should aim to achieve and (c) draws out methods that are of particular importance to organisations involved in development and operation of safety-critical systems. The position paper summarises lessons learned on how to improve safety culture, such as engaging with staff, and clearly communicating behavioural expectations. These lessons draw on evidence of what has and “has not” worked. There are well known examples of organisations that had been regarded to be industry leaders, subsequently suffering major accidents due to the erosion of their safety culture, changes in organisational imperatives and a loss of corporate memory of past incidents. The position paper offers some tactics for guarding against the erosion of safety culture. It concludes by reinforcing the position that safety culture influences all aspects of safety performance and all stages of the system lifecycle, including design, safety assessment and assurance, manufacture, operations and maintenance. The position paper will help organisations understand how they can effectively assess, improve, and maintain their safety culture.