To mount a response to threats to peace and security, should states act unilaterally, seek to build ad hoc coalitions of the willing, or work through multilateral institutions? What are the benefits and risks of global cooperation? This seminar interrogates these questions by examining the role that international organizations play in responding to global threats in the modern era. The first section focuses on the advent of the modern global institutional architecture, considering its historical context, theoretical underpinnings, sources of legitimacy and power (or lack thereof), and the role of regional, subnational, and nongovernmental actors. The second section considers the efficacy of global institutions in responding to transnational threats through recent case studies, including the Syrian civil war, the Paris Climate Accord, the Iran Nuclear Deal, and 2014-2016 Ebola outbreak in West Africa. The final section explores the future of the liberal world order and its institutions, and considers alternative models of global cooperation. Students may write a long policy memo for an additional unit of credit. Enrollment is capped. Course is cross-listed with LAW 5039.