Framed by a new and substantial introductory chapter, this book collects Stefano Guzzini’s reference articles and some less well-known publications on power, realism and constructivism. By analysing theories and their assumptions, but also theorists following their intellectual paths, his analysis explores the diversity of different schools, and moves beyond simple definitions to explore their intrinsic tensions and fallacies. Guzzini’s approach to the analysis of power – within and outside International Relations – provides the common theme of the book through which the theoretical state of the art in IR is reassessed.A novel analysis of power and the potential limits of realism and constructivism in International Relations, Power, Realism and Constructivism will be of interest to students and scholars of international relations, international political economy, social and political theory, and the study of power.