This study examined whether vocabulary knowledge is sufficient for second language (L2) word-meaning inferencing. Specifically, it investigated the role of the learner's sensitivity to a word's morphological structure (referred to 'morphological awareness' or 'MA' hereafter) as additional support that enhances multi-character word-meaning inferencing in adult learners of Chinese as a second language. Two hypotheses were tested: (i) L2 vocabulary knowledge is the sole predictor of word-meaning inferencing involving morphologically simple multi-character words. (ii) L2 vocabulary knowledge and MA jointly contribute to word-meaning inferencing involving morphologically complex multi-character words. A set of paper-and-pencil tests was administered to 56 English-speaking learners of L2 Chinese, measuring their L2 vocabulary knowledge, MA, and word-meaning inferencing ability. The results are as follows: L2 vocabulary knowledge contributed directly and consistently to inferring the meanings of multi-character words. Yet, L2 vocabulary knowledge was not the sole predictor of L2 word-meaning inferencing; L2 MA made an additional unique contribution. Last, L2 MA contributed indirectly to L2 word-meaning inferencing through the mediation of L2 vocabulary knowledge.