The purpose of this study is to determine whether extensive reading has positive effects on developing inferencing skills. Extensive reading is a language learning method of reading large amounts of comprehensible texts. This method limits the use of dictionaries while reading; therefore, extensive readers have greater practice in dealing with unfamiliar words than non-extensive readers. One of the ways to deal with unfamiliar words is to infer the meaning of the word using contextual clues. Knowing how to infer the meaning of unknown words is a helpful skill for language learners. Due to the fact that extensive readers have a greater practice in dealing with unknown words, this study examines whether there are any differences in the precision of inferencing skills between extensive readers and non-extensive readers. There were 39 participants analyzed in this study, 28 non-extensive readers and 11 extensive readers. The results showed that extensive reading has positive effects on language learners’ inferencing skills. In terms of accuracy, we could not see a statistical difference; however, the extensive readers had a higher percentage in accurately inferring the word meaning. In terms of the use of knowledge sources, extensive readers were able to choose the appropriate knowledge source when inferring the target word. These results indicate that extensive reading can enhance language learners’ inferencing skills.