The “mediation” and “use” notions are frequently employed in researches in the field of information science and communication in France. The main purpose of this article is to reflect on these two notions, so as to reveal, in the absence of its “natural” evidence, some problems, resources and risks. The idea of mediation is originated in anthropo-social sciences and provides means to describe with a certain precision, information-communication processes; it allows socially requalifying the dynamics and regimes of culture and leads the researcher to question one’s own place in the circulation of social knowledge. The idea of use keeps a historical link with the media reception studies carried out by the North-American “administrative” sociology and relates to functionality, even if not reducing it to technology. The mediation (mediations) and the use do not differ because of their respective objects, but because of the perspective effect they produce and the very different ways they glimpse at the place of communication in informational practices. It can therefore be asserted that in a communicational perspective, the notions of mediation, practice and use operate together. However, this does not take place without tensions and paradoxes.