Through a comparison of the telecommunications sectors in four small EU-countries, this study assesses regulatory authorities at international, supranational national and regional level within and between sectors (telecom, media, general competition) successfully offering a new and more holistic perspective of multi-level regulation in network industries. Rather than focusing exclusively on features of the individual sectoral regulatory agency this book considers all the regulatory actors at different government levels involved in the regulatory arrangement of a specific market and their interplay. Furthermore, it assesses the design and functioning of these multi-level regulatory arrangements in terms of decision-making coordination and exemplifies how national telecom regulatory agencies share and coordinate regulatory decisions with other regulatory authorities at EU-, national and regional level within the sector and across sectors (media, general competition) in order to provide coherent regulation of telecom markets. Combining theories of regulatory governance and public administration the book analyzes how specialization and coordination within these regulatory arrangements influence the relative decision-making power and autonomy of the sectoral regulatory agency, as well as how these arrangements adapt to overcome regulatory incoherencies.