The paper discusses the ‘psychological reality’ of human languaging. Basing on the dialogical and distributed arguments, the point of departure is in observations of the actualities of languaging in different modalities and environments. Arguing against the psychological reality of ‘mental grammars’ as storages of internal rules and representations, the concept of decontextual and amodal language knowledge is replaced by a know-how that is associated both with the modality and indexicality of usages. Further, instead of a ‘grammar’, the reservoir of agentive knowledge is approached as a personal repertoire that is discussed, using the concept of timescales, as an assemblage that develops during the agent's personal trajectory, but that at the same time is made possible by developments over cultural-historical and evolutionary timescales. The discussion is associated particularly with the field of applied linguistics, and aims at offering new theoretical arguments for the research on language learning and teaching.