After decades of neglect, vocabulary is no longer a victim of discrimination in second language learning research, nor in language teaching. The acquisition of vocabulary has assumed a more important role in learning a second language. Basically, in L2 teaching and learning vocabulary through reading, there are two instructional techniques: incidental learning and intentional learning. This study explores the role of reading in L2 vocabulary acquisition, and the effect of different vocabulary instructional techniques on the vocabulary learning of Chinese university ESL students of different levels.