Risk is a concept that has become widespread and used in several research fields within the social and hard sciences, mainly to address probabilities that something bad can happen, including adverse effects and uncertain outcomes. The goal of this introductory chapter is to deepen the understanding of risk from different theoretical perspectives and to contrast them by formulating key implications that will serve as the foundation for the subsequent chapters of this book. The chapter explores why it is essential to examine risk and risk thinking across two disciplines—Security Studies and Risk Governance—as these two scholarly fields were the point of reference for the theoretical and subsequent analytical framework of the RISKSEC2.0 project. We will illustrate key distinctions and potential overlaps between risk understandings from the two disciplines, as they emerge from separate epistemic communities. In addition, we will propose interfaces on risk from Security Studies and Risk Governance, while reflecting on their implications.