<p>The ability of second language (L2) learners to guess the meanings of unfamiliar words, which is known as lexical inference, is crucial for learning words and for reading comprehension. However, the extent to which L2 learners can make effective use of the contextual resources surrounding unfamiliar words remains uncertain, as many L2 studies seem to suggest a low success rate for lexical inferencing in context; furthermore, whether the relationship between contextual richness and the success of lexical inferencing is influenced by L2 learners’ linguistic knowledge (i.e., vocabulary and grammatical knowledge) is undetermined. Sixty-six L2 Chinese learners who were attending Chinese universities participated voluntarily in this study. All the participants completed four computerized tasks: a short-term memory task, a vocabulary knowledge task, a grammatical knowledge task, and a lexical inferencing task with three contextual conditions. The results revealed that: 1) regardless of their linguistic knowledge, L2 learners performed better in lexical inference when provided with a more informative context compared to a less informative or a non-informative context, indicating that the degree of contextual richness plays a significant role in L2 learners’ success; 2) L2 learners with greater linguistic knowledge performed marginally better when inferring the meanings of unknown words in the more informative context than did those with less linguistic knowledge; and. 3) although L2 learners’ linguistic knowledge did not generally have a moderating effect on their lexical inference via the use of contextual information, there appeared to be some complexity in this relationship for participants with greater linguistic knowledge.</p>