Implementation will be difficult, because of the proliferation of new, uncoordinated planning mechanisms and the prescriptive approach of Grenelle, which runs counter to the current trend toward greater flexibility in planning (planning by ordonnance). In the Paris-IDF region, such coordination is bound to be complicated due to its position as a global metropolis viewed by the government as strategic, the many players involved in its governance, the fragmentation of fields of intervention, and the diffuse and often opaque nature of the decision-making process. This is all the more true when one attempts to describe “the system of green growth governance in Ile-de-France,” as “green growth” is not currently the explicit object of governance. The region is characterised by a surfeit of administrations - the famous institutional millefeuille comprising nearly 1 300 communes - which frustrates horizontal and vertical coordination among public players. Consequently, it is difficult to strike a consensus on a coherent and shared vision of the region. This fragmentation of local authorities is a handicap for green growth, which requires coordinated spatial approaches.