This chapter explores realist and liberal theories which are often thought of as the "conventional wisdom" in global governance. The European experience with war and imperialism has shaped the realist framework for understanding international relations. Outside Europe, many have embraced this framework and its worldview because it generates valuable insights and lessons regarding world politics. The chapter examines realist explanations for the nature of international organizations why they are created and how they work in the context of sovereign states struggling for power in a hostile international environment. It details the philosophic underpinnings of realist theory in order to gain historical insight into contemporary realist thought. Contemporary realist analyses of international organization and cooperation often employ game theory as a tool to explain why cooperation is difficult under conditions of anarchy. International organizations can help counter the free rider problem absent the hegemon by identifying unacceptable barriers to trade and providing a neutral forum for settling trade disputes.