Unknown word is a major impediment in L2 reading comprehension. In order to investigate how Chinese EFL learners tackle unknown words in reading, this book explored the lexical inferencing of Chinese learners in terms of the intent, the clue use, the procedure, the processing type, the adaptability, and the success of lexical inferencing as well as the subsequent lexical knowledge acquisition. Chinese EFL learners at four stages of English learning participated in this study. Questionnaire, think-aloud introspection and a surprise test were employed in this study. Data were analyzed quantitatively and qualitatively to identify the type & amount of clue use, the event sequence of inferencing, the processing type & adaptability, the outcome of lexical inferencing, and the subsequent vocabulary knowledge acquisition in lexical inferencing.