The present book is the first output of the “Research of Development Project”: “Der-2015-68768N (EUDisCoop Project) International Administrative Co-Operation in Tax Matters and ADR of Transnational Tax Disputes: Features of an Institutional Architecture from a European Perspective”, sustained by the Spanish Minister of the Economy and Competitiveness 2016-2019 and part of the Excellence Network Der 2017-90874-REDT-G.O.T.A. INTAXCOOP&GOV: “The Global Observatory on Tax Agencies: Towards to the International Tax Cooperation and Global Tax Governance” (2018-2020). In particular, this book contains the proceeds of the International Congress 2017: “International Administrative Cooperation in Tax Matters and Tax Governance” (26th and 27th January 2017, University of Barcelona). The new century highlights the relevance of international tax cooperation policies within a global tax governance environment. In line with the recent launching of the Platform for Collaboration on Tax promoted by the United Nations, the International Monetary Fund, the Organisation for Economic Cooperation and Development and the World Bank, this book deals with fundamental issues related with the role of international institutions towards the fostering of a global tax cooperation environment. This book addresses the principles, sources and costs of the international tax cooperation and global tax governance agenda, as well as the role played by taxpayers’ rights in the interaction with modernized and digitized tax administrations from a comparative perspective. There is no doubt that “International Tax Cooperation” and “Global Tax Governance” have achieved a pivotal role in the new global Economy and Legal Order and this book is meant to address in a comprehensive way these very topical developments.