This chapter looks back at how safety and security have developed in hazardous technologies and activities, explaining what has become an intersection between the two in both strategies and management practices. We argue for the connection to be made between social expectations of safe and secure societies and the limits to management and technical performance. In the first part of the chapter, conceptual similarities and differences are addressed and we distinguish three scientific and contextual vantage points for addressing how safety and security are converging: the conceptual approach, the technical and methodological approach, and the management and practice approach. We then go on to show that, as professional areas, safety and security have developed in different ways and supported by quite separate scientific and technological fields. Finally, we present the organization of the book.