The analysis of a 190,000-word-unit corpus (VU Amsterdam Metaphor Corpus) by Pragglejaz Group revealed that 13.3% of all words are metaphorical, with only 4.36% of these metaphorical words used as metaphors. In previous studies, much attention has been paid to the linguistic and conceptual dimensions of metaphor. With the communicative dimension of metaphor is attracting more and more scholarly attention, Deliberate Metaphor Theory (DMT) is proposed. In this theory, only deliberately used metaphors are interpreted metaphorically by the addressee. DMT, by introducing the notion of ‘deliberateness’, can enlarge the scope of metaphor. The paper points out the major challenges facing DMT and future developments, hoping to bring more attention to this new line of metaphor research.