Up to now the discussion of genres has been oriented rather exclusively towards text-types in the literary-system, and its scope has mostly been typological. In contrast to these approaches this paper aims at a systematic explication of the notion of genre in a science of the media on a constructivist epistemological basis conceiving of genres in terms of cognitive concepts.A constructivist theory of genre concentrates on functions, it strives for homogeneous argumentation, and it tries to establish a general theory of media genres which is able to explain the function of genres in the media in general.