This article presents the early stages of the implementation of electronic monitoring (EM) in France, from the end of 2000 until the beginning of 2004. The first part discusses the origins of EM legislation, organisation and testing. The second part outlines the results of the pilot phase, based on a qualitative and quantitative study conducted by the authors: they describe the main characteristics of French EM and of the monitored population; they go on with an analysis of the ways EM has influenced the work of the prison guards and social workers involved. The final part of the article is devoted to a discussion of the prospects of EM in France.