Following a presentation of the article's main argument that decentralization is a reaction in line with a broader phenomenon greatly affected by economic integration, this article reviews concepts of region and recent policy developments in this area in Quebec. Given that the articulation of a successful decentralization policy necessitates a good understanding of its causes and effects, the article follows with an examination of the main causes of decentralization: economic integration and the spatial and sectorial recomposition of the accompanying activity, the decline of Keynesianism, the profusion of social actors, the fiscal crisis, local development, the electronic highway, the consolidation of regional capitals, struggles between levels of government. This is followed by a consideration of the very significant inter-regional disparities in Quebec, a crucial factor in determining the modalities of a regionalization policy. The conclusion offers a discussion of the objectives and means of decentralization, and it stresses the importance of distinguishing between the supply and the demand of public goods and services in the various regions so as to foster the development of effective decentralization institutions. The author suggests that considerable importance should be accorded to organizing cooperation between the various decentralized authorities and the use of result-oriented directives which leave the choice of means to decentralized authorities. The adoption of a policy for cities and regions and the establishment of a regional Council are also discussed.