Nearly all countries worldwide are now experimenting with decentralization. Their motivation are diverse. Many countries are decentralizing because they believe this can help stimulate economic growth or reduce rural poverty, goals central government interventions have failed to achieve. Some countries see it as a way to strengthen civil society and deepen democracy. Some perceive it as a way to off-load expensive responsibilities onto lower level governments. Thus, decentralization is seen as a solution to many different kinds of problems. This report examines the origins and implications decentralization from a political economy perspective, with a focus on its promise and limitations. It explores why countries have often chosen not to decentralize, even when evidence suggests that doing so would be in the interests of the government. It seeks to explain why since the early 1980s many countries have undertaken some form of decentralization. This report also evaluates the evidence to understand where decentralization has considerable promise and where it does not. It identifies conditions needed for decentralization to succeed. It identifies the ways in which decentralization can promote rural development. And it names the goals which decentralization will probably not help achieve.