This lecture is about constructing implicitness in diplomatic discourse, which involves intra-lingual translation both in ST and in TT. A review of implicitness in diplomatic discourse, which often demonstrates a scripted feature, shows that notions of ambiguity, fuzziness, generality, and vagueness put forward by Zhang (1998) can be employed to scrutinize the construction of implicitness via lexical choice. Viewed in terms of Hallidayian linguistics, the construction of implicitness, in both ST and TT, bears a strong interpersonal prominence. As shown in the analysis of the implicitness found in the diplomatic discourse around the 2001 Air-Collision Incident, the interpersonal prominence is governed by national interest concerns of the discourse producers. A tentative model of creating and translating lexical implicitness in diplomatic discourse is suggested. As illustrated in the model, the translation-engendered implicitness in diplomatic discourse is a textual manifestation of the interpersonal prominence in the international arena of foreign affairs.