Annotation "We do not know where Silicon Valley is really located," Feldman writes, because these types of organization, when they are dynamic, are moving and fluid. Innovation and production ecosystems or clusters are proliferating today because they seem to be adapted to the demands of innovation, growth and employment. The process leading to their institutionalization escapes a summary analysis of the behavior triggered by monetary incentives or, at the very least, makes it richer. The relational aspect becomes predominant, the interactions between the participants testify to the difficulty of separating the geographical and social dimensions. In the most prominent American clusters, public/private linkages and the building of social links express the centrality of networks in the innovation process. The European vision seeks to articulate entrepreneurial discoveries with vertical public interventions. The competitiveness poles in France suffer from the fact that public choices seem to be torn between two contradictory objectives: efficiency and equity.