- In an age of globalization, many regulatory problems lie beyond the reach of the nation state. Solutions have to be found which extend beyond territorial borders. Normally, we would expect international law to be the appropriate forum for addressing these issues, but this assumes formal consensus among states, which is difficult to obtain. Therefore a number of informal structures of pragmatic public governance have emerged, as an alternative to formal law-making processes, operating within the transnational space between national and international law. These structures display a great variety, ranging from loose transboundary networks linking national administrative agencies and transnational expert committees, to networks involving administrative staff of international organizations. They work out their own agendas and, in some cases, have emancipated themselves from formal national or international parent institutions. These network-like structures have become important building blocks of global governance, addressing today's regulatory issues in a more flexible way. At the same time, their informality raises crucial questions of legitimacy. This book shows how transnational administrative governance leads to a paradox: while it performs well in many areas, providing solutions that are not achievable by state and international law, its informality profoundly lacks legitimacy in a strict sense. The book explores, from a socio-legal perspective, a broad range of legitimation mechanisms of different types and quality, and it shows that there can be a fit between certain forms of legitimation and specific governance constellations.