By Lenz, Tobias

How and under what conditions does the European Union (EU) shape processes of institution building in other regional organizations? Interorganizational Diffusion in International Relations: Regional Institutions and the Role of the European Union develops and tests a theory of interorganizational diffusion in international relations that explains how successful pioneer organizations shape institutional choices in other organizations by affecting the institutional preferences and bargaining strategies of national governments. The author argues that Europe’s foremost regional organization systematically affects institution building abroad, but that such influence varies across different types of organizations. Mixing quantitative and qualitative methods, it shows how the EU institutionally strengthens regional organizations through active engagement and by building its own institutions at home. Yet, the contractual nature of other regional organizations bounds this causal influence; EU influence makes a distinguishable difference primarily in those organizations that, like the EU itself, rest on an open-ended contract. Evidence for these claims is drawn from the statistical analysis of a dataset on the institutionalization of 35 regional organizations in the period from 1950 to 2017 as well as detailed single and comparative case studies on institutional creation and change in the Southern African Development Community, Mercosur, the Association of Southeast Asian Nations, and the North American Free Trade Agreement.


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Oxford: Oxford University Press [open access], 2021

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“For more than 60 years, international relations scholars have tried in vain to understand the relationship between Europe and regional organizations in the rest of the world. Look no further – here is the answer that will shape the debate for decades to come! In this ground-breaking book, Tobias Lenz covers all relevant regional organizations since 1950 and explains if, why and in what ways the European Union shapes their process of institution building. No serious scholar concerned with international and regional organizations, the EU’s role in the world, and diffusion can afford to miss what he has to say.” – Fredrik Söderbaum, Professor of Peace and Development Research, University of Gothenburg, Sweden

“This brilliant book is unique in shedding a radically new light on why and how regions around the world evolve over time in the shadow of the European Union (EU). Tobias Lenz convincingly argues that we live in a relational world, and that in such a world, the EU has been an organizational pioneer, affecting other regional organizations by shaping the way their national governments think and act. This book is destined to constitute THE main reference in the story of diffusion of Europe’s approach to regional integration. No scholar or policy makers can afford to ignore it.” – Kalypso Nicolaïdis, Chair in International Affairs, School of Transnational Governance, European University Institute, Florence, Italy

“This is a phantastic book! It demonstrates that the European Union (EU) is indeed the dominant model of institutional diffusion to regional organizations in the rest of the world. However, diffusion does not lead to institutional convergence, but regional organizations across the world exhibit distinct features. National governments are no dummies simply downloading “EU software”. They craft and filter EU features through their own preferences and strategies leading to the selective adaption of institutional models. Lenz develops his argument through a carefully designed mix of quantitative analyses complemented by detailed case studies. This book will have a lasting impact on both comparative regionalism and diffusion studies in general.” – Thomas Risse, Professor of International Politics at the Otto Suhr Institute, Freie Universität Berlin

“This book tackles an empirical conundrum in a very theoretically grounded way: On the one hand, the number of organizations that group together regional sub-sets of pre-existing national states has proliferated across the entire planet in recent decades; On the other, one of these – the European Union – is almost universally regarded as “unique” in its supra-national competences. Exploiting a comprehensive and original dataset with the formal characteristics of no less than 36 regional organizations, Lenz finds part of the answer in the process of institutional diffusion, both explicit thanks to the EU’s efforts to clone itself and implicit in the efforts of others to imitate its success. No one attempting to develop a universally applicable theory of regional integration can afford to neglect Lenz’s findings.” – Philippe C. Schmitter, European University Institute, Florence, Italy

“A fascinating and timely examination of the influence of EU institutions on other regional organizations. Lenz breaks new ground in his conceptualization of transnational diffusion and puts it to work to explain heterogeneity in regional institutionalization. The EU may influence institutional preferences and strategies in other regional contexts but regional institutions around the world do not merely emulate the EU. Empirical tests spanning large-N study, process-tracing, and a paired comparison suggest that other regional institutions might have indeed been less institutionalized in the absence of interaction with the EU. The book is a must read for scholars of regional institutions and transnational diffusion alike.” – Etel Solingen, Distinguished Professor and Thomas T. and Elizabeth C. Tierney Chair in Peace and Conflict Studies, University of California Irvine