This book provides an introduction to positivist-pluralist theories of international relations (IR) which emerged during the early-and mid-1950s along with Marxist political economic and non-Marxist economic theories of IR. Positivist and Political-Economic Theories of International Relations is an in-depth critical study of texts and literature which highlight IR's methodological pluralism even after it gained maturity. It examines how pluralist political status quo and radical economic criticism coexist in discrete areas of the discipline. Insights are provided into key positivist liberal-pluralist theories, namely decision-making approaches, and theories of integration, regionalism, interdependence, and regime. It discusses the four political economic and critical theories of Marxism, dependency, world systems, and international political economy. The book, as an advanced supplementary reader, will be of great interest to researchers and students of international relations, history, law, and the multidisciplinary social scientific field of political economy.