 Knowledge is important for safety management. In a given situation that may affect safety such as a malfunction, an incident or an accident, knowledge must be mobilized to make the right decision. Knowledge of the procedures to apply, knowledge of the operation of the devices, knowledge of the physical, chemical and mechanical processes at work, technical knowledge and so on. For example, if we do not know what physical or chemical phenomenon is happening in our installation, we may not be able to apply the right action to solve the problem. So we must make the decision knowingly, that is mobilizing knowledge to analyze the situation and to solve the problem. It is absolutely impossible for one person to solve a complex problem alone. Very often no one at this level is able to understand the entire situation and to know all the elements required to solve the problem. But everyone must be able to identify the necessary knowledge required by the situation and know where to look for it. Knowledge can take very different forms and be stored in different places. It is first and foremost stored in the brains of collaborators. An obvious can ask for help from a more expert person. Often problem solving requires the collaboration of several people who will have to combine their knowledge to find an appropriate solution to the situation. It is also stored in documents, procedures, rules, technical documentation and so on. We are generally available in knowledge spaces. Finally, it can be stored in available knowledge management systems, knowledge books, experience feedback and so on. The role of the leader is multiple. He must first identify the key knowledge of his or her activity, ensure that it is correctly stored, regularly updated and easily accessible for employees. He must then motivate employees to develop their competencies by systematically mobilizing the knowledge accumulated in the organization. Finally, he or she must create the organizational conditions necessary for the development of new knowledge. To sum up, he or she must ensure the creation of new knowledge, its retention and its sharing within his or her department. In this part, Jean-Louis and I will help you understand how a leader can improve knowledge management and learning in a company in order to increase safety. First, we will define the nature of knowledge and the correlating consequences. Second, we will present the main processes that support knowledge creation, retention and sharing. In a third step, we will answer two key questions, how an organization learns and what are the main barriers of organizational learning.