The term ‘Decentralized Cooperation’, coined in the 1980s, is interpreted differently by various organisations involved in development cooperation. However, there are points of convergence among these interpretations that suggest a common definition involving: (a) the lead actors (local governments), (b) an overarching objective (sustainable local development) and (c) the nature of activities carried out (exchanges and support). From a historical perspective, the origin of Decentralized Cooperation is two-fold. On the development cooperation scene, the concept emerged when the array of actors involved in development projects widened as a result of major changes in aid themes and approaches. In the field of international relations between local governments, Decentralized Cooperation activities appeared as the scope of municipal twinnings also widened accordingly to involve partners from countries in development or in transition. Today, Decentralized Cooperation continues as an evolving concept located at the intersection of its two parent fields: development cooperation and international municipal relations. At this intersection, a fusion of experiences, resources and ideas is taking place. Copyright © 2003 John Wiley & Sons, Ltd.