Analysis suggests that Korean children use different sentence-ending morphemes to encode different degrees to which they assimilate information into their knowledge system, and that they acquire such epistemic distinctions at a very early age. The study focuses on the occurrence of the modal markers "-ta,""-e," and "-ci," acquired during the first year of language development. The data were derived from a longitudinal study of the spontaneous speech of two monolingual Korean-speaking children. This study represents additional cross-linguistic evidence that speakers are sensitive to, and capable of grammaticizing into their modal system, different levels of status in their knowledge structure. (MSE)