This publication analyzes the impact of fiscal decentralization and the resultant issues and challenges that countries face in practice. It traces the evolution of fiscal decentralization as a significant and consequential global reform that has made subnational governments' key public sector actors in a majority of countries. This note touches upon its various aspects: incidence and presence in the world; foundation in economics; impact of a list of outcomes, including economic growth, macroeconomic stability, poverty and income distribution, and service delivery and political accountability. It confirms the positive overall impact of decentralized systems, especially when they are well designed and implemented with examples from around the world, including those from Asia and the Pacific.