This chapter highlights the challenges presented by international politics. Much of what happens in British politics occurs because of Britain's relationship to the international stage. Relationships to other states, international bodies, and the international economy need to be managed by the UK's political leaders and foreign and defence bureaucracies, to manage how to deploy Britain's voice in international matters. Then there is the delegation of powers to international organizations and the making of treaties. The chapter specifically examines foreign policy and focuses on how functions are delegated to international organizations. It tells the story of the European Union (EU) as one of the most important international delegations culminating in the story of Brexit. This leads to a discussion of the UK's defence and security role. One key theme of the chapter is how success and failure in international politics feed back into domestic politics.