International audienceThe purpose of this article is to define the conditions of authority construction in participatory mediatized spaces, such as online multiplayer games or discussion forums. This construction of authority is, as shown, complex in these areas. Indeed, they present a paradox: they provide many opportunities of interaction while facilitating refusal to start exchanges, and exclusion as well. We show that the participants develop a process called communicational reflexivity, whenever they get involved in any authority construction project. On the one hand, this process is what allows them to determine what behavior they should adopt in order to increase their chances of being accepted by other people as exchange partners. O...