This chapter unpacks the complex relationship between international organizations and peaceful change in the international system through various perspectives on international relations. We identify three types of peaceful change associated with international organizations: institutional change within IOs, interactional change among IOs, and transitional change involving IOs and power dynamics in the international system. The latter has the potential to bring about a “maximalist peaceful change,” resulting in profound positive changes in international relations and human life. However, it also carries significant risks. As great power rivalry intensifies and challenges to the existing liberal international order grow, understanding the role of international organizations in promoting or hindering peaceful change becomes crucial. This chapter serves as an introduction to the volume, providing an overview of its content and summarizing the major findings of other chapters. The book not only diagnoses the ability of international organizations to facilitate order transitions but also offers suggestions to address their current shortcomings in promoting peaceful change.