Song, Mean-Young. 2009. The Semantics of Epistemic Modality. English Language and Linguistics 28. 301-342. According to the standard semantics of epistemic modals, including Kratzer (1979 and 1991), epistemic modals are dealt with on the basis of entailment by what is known. The problem with the treatment is that the entailment from what is known is not appropriate for the semantics of epistemic modals in some cases. Another problem to note in the treatment of epistemic modality is that must p, where p is a prejacent, does not necessarily mean that p. To remedy this, this paper argues that evidentiality must be incorporated into the semantics of epistemic modals, which implies that epistemic modals signal that a certain conclusion is reached from a body of evidence. Based on this, the present study argues that the semantics of epistemic modals consists of an evidential component which signals a source of information and an epistemic component which reflects the speaker’s assessment of the source of information. This may assist in understanding the speaker’s choice of epistemic modals in an utterance and the difference in strength between epistemically modalized sentences and unmodalized ones.