Adequate reading literacy skills are essential for receiving formal education and subsequently gaining full participation in society. Research into L2 reading demonstrates that L2 vocabulary knowledge is key for developing learners’ L2 reading comprehension. This chapter looks into the vocabulary knowledge measured by word associations and sheds some light on the implication of developing vocabulary knowledge to facilitate young learners’ L2 reading literacy for Hong Kong primary schools. The results show that word knowledge and word class have an important influence on young L2 learners’ word association patterns. A number of implications are proposed, including enlarging children’s vocabulary size to reach a threshold level for L2 reading, utilizing graded readers to control vocabulary and teaching words of different word classes with their preferred collocates. Copyright © 2019 The Author(s).