The United Nations Secretary-General and the United Nations Security Council spend significant amounts of time on their relationship with each other. They rely on each other for such important activities as peacekeeping, international mediation, and the formulation and application of normative standards in defense of international peace and security—in other words, the executive aspects of the UN’s work. The edited book The UN Secretary-General and the Security Council: A Dynamic Relationship aims to fill an important lacuna in the scholarship on the UN system. Although there exists an impressive body of literature on the development and significance of the Secretariat and the Security Council as separate organs, an important gap remains in our understanding of the interactions between them. Bringing together some of the most prominent authorities on the subject, this volume is the first book-length treatment of this topic. It studies the UN from an innovative angle, creating new insights on the (autonomous) policy-making of international organizations and adding to our understanding of the dynamics of intra-organizational relationships. Within the book, the contributors examine how each Secretary-General interacted with the Security Council, touching upon such issues as the role of personality, the formal and informal infrastructure of the relationship, the selection and appointment processes, as well as the Secretary-General’s threefold role as a crisis manager, administrative manager, and manager of ideas.