This chapter highlights that there has been a path towards decentralisation in a majority of OECD countries over the past decades. The chapter also underlines that deecentralisation trends around the world have often gone hand in hand with an upscale in subnational governance through amalgamations, inter-municipal cooperation, metropolitan governance, and the strengthening of regions. Municipal fragmentation has driven policies encouraging or imposing mergers or cooperation. In parallel, there has also been an increase in asymmetric decentralisation, i.e. the fact that governments at the same subnational government level have different political, administrative or fiscal powers. While asymmetric decentralisation appears more “natural” in federal countries, it is increasing in unitary countries. Finally, the chapter shows that decentralisation is too often understood as a simple increase in the power of local governments. The reality is much more complex, as most responsibilities are shared across levels of government. Decentralisation is about reconfiguring relationships between the central government and subnational governments towards a greater cooperation and a strategic role for national/federal governments.