Prevention of Accidents at Work collects papers presented at the 9th International Conference on the Prevention of Accidents at Work (WOS 2017) held in Prague, Czech Republic, on October 3-6, 2017, organized by the VSB-Technical University of Ostrava. The conference on current issues within occupational safety is organized under the umbrella of Workingonsafety.net (WOS.net). WOS.net is an international network of decision-makers, researchers and professionals responsible for the prevention of accidents and trauma at work. The network aims to bring accident prevention experts together in order to facilitate the exchange of experience, new findings and best practices between different countries and sectors. WOS.net is supported by the European Agency for Safety and Health at Work (EU-OSHA). The overall theme is safety management complexity in a changing society, with the motto: Do we need a holistic approach? Underlying topics include: Foundations of safety science: theories, principles, methods and tools; Research to practice: achievements, lessons learned and challenges; Risk management and safety culture: case studies, best practices and further needs; Safety regulation: reasonable practicable approach; Education and training: prerequisite for safety; Complexity and safety: multidisciplinarity and inter-stakeholder views. Prevention of Accidents at Work should be valuable to researchers, policy makers, safety professionals, labor inspectors, labor administrators and other experts in the prevention of occupational accidents.