In this article, the implementation of French reforms establishing new local cooperation institutions are analysed. The considerable numerical success, on a national scale, of this new formula calls for reflection on the interplay between national variables and local characteristics. One might be tempted to assume a very strong national dimension to the issues, and a major role of the state in directing related developments. However, an observation of the fairly impressive variation in local implementation highlights a marked territorial differentiation. Nevertheless, exchange and imitation of successful cooperation formulas suggest there might be a tendency towards new forms of convergence, less in a vertical than in a horizontal sense. The argument is based on three steps: a description of the system and of its apparent coherence, an analysis of its implementation, and an account of local variables, involving tendencies to both convergence and to the diversification of “regional configurations”.