Contemporary researchers consider mediation as a kind of language activity where both receptive (listening and reading) and productive (speaking and writing) activities interact. These kinds of language activity are examined from a psychological point of view to make the practical development of the language activities more efficient and the teaching strategies more powerful and accomplished. Mediation as a kind of language activity must be taught and consequently psychological reasons of studying mediation should be studied thoroughly. Interaction of receptive and productive language activities implies the interaction of psychological grounds of listening and speaking, on the one hand, and reading and writing, on the other hand. Such interaction cannot be considered as addition one language activity to another. Apparently it is some kind of a complicated integrated unity of psychological entities. The paper is focused on psychological aspects of mediation as a language activity. It analyses different aspects of mediation and some issues of their application in teaching practice.