The present study examined how Japanese EFL learners infer the meaning of unknown words from discourse information, focusing on their depth of vocabulary knowledge (DVK) and availability of contextual cues for lexical inferencing. A total of 70 Japanese undergraduates performed a lexical inferencing task in a single sentence and a text (i.e., sentence-based and discourse-based inferencing tasks). In both inferencing tasks, five target words were presented to the participants with or without local cues (+Local and -Local conditions): +Local strongly constrained the inferable meanings of target words and -Local did not. The participants' responses were scored by a 3-point scale: unsuccessful, partially successful, and successful. The scores showed that (a) EFL learners can infer the meaning of unknown words more successfully by using local and global cues than by using only local cues, and (b) EFL learners with greater DVK can make a better use of the global cues than those with smaller DVK. Furthermore, the qualitative analysis showed that (c) the learners changed non-working local cues into effective ones in discourse-based lexical inferencing by connecting local cues with available discourse information.
