This book stands as the full body of scholarly work on western theories of social sciences. The book contents three chapters. The first part gives the overall scenario of theories, the second part provides the pathway to research destination – the research method, and the third and final part is the destination of the substantive field of study and the roles of international organizations on social, political, economic, environmental regimes creation as well as to other social and development functions of international organizations. Sociology examines the social actors’ activities in society and social problems. Western Scholars have developed many social theories, which address the underlying causes such as social conflicts and inequalities, and many formal and informal social organizations are involved to minimize the challenges of inequalities. The study of social organizations is a relatively new phenomenon in sociology. Broadly its historical root can be traced from Greek civilization (Plato, Aristotle), and it has mostly flourished since the Enlightenment Era. However, empirical studies show that the scientific study of organizations began only from the 19th and 20th century. Among the scholars of these centuries, the contributions of Karl Marx, Ferdinand Tönnies, Émile Durkheim, Ludwig Gumplovicz, Vilfredo Pareto, Max Weber, and Talcott Parsons are considered as pillars of sociology. This book intends to answer the broad and major questions of theories, methods, and the international organization studies in social sciences, particularly in sociology and to provide the basic concepts of social theories, application of methods in research (qualitative), and elaborate the factual reality "why study of international organization is also subject of sociological study". The book presents the perspectives of organizational sociology in way that scholarly readers can see the linkages political sciences, sociology and slightly economic in addressing the roles and issues of the international organizations.