Aiming for a more effective and efficient response to diverse and multidimensional threats, an increasing number of defense and security organizations, the United Nations, NATO, and the EU embrace the concept of resilience in their security strategies and policies. This article provides a brief overview of the concept, a sample of definitions used in policy documents, and the types of problems they seek to resolve. Then we introduce the reader to the 15 articles published in the Summer and Fall 2020 issues of Connections that present the evolution of the concept of resilience and its implementation by and within political, defense, and law enforcement organizations, as well as its anticipated contribution to cybersecurity, disaster preparedness, peacebuilding, post-conflict restoration and countering hybrid threats.