Abstract : Knowledge management relies – willingly or unwillingly – on three components: organizational structures, communities of practice, and material settings. In an organization, those three components are interdependent, that is, each of them enters into the composition of the others. They are also resistant to each other, which means that each of them marks the limits of the others‟ action. This relationship allows us to understand why a knowledge management system, if conceived strictly from the point of view of organizational structures, does not benefit from the support of communities of practice. It also suggests that emphasis should be put on the settings that reinforce both organizational control and the communities‟ autonomy. Finally, this allows us to understand that the appropriation of such a setting by communities of practice implies a slight modification of organizational structures.