There are three purposes of this paper, the first of which is to elucidate the theory and principles underlying extensive reading. Long-held principles will be discussed in light of practical classroom and contextual considerations. Secondly, a critical summary of current research on extensive reading that has been conducted in English as a Second Language and English as a Foreign Language contexts and has been published over the last five years will be presented. By highlighting the vast benefits of extensive reading on improving many aspects of L2 learners' language proficiency, we hope to encourage greater implementation of extensive reading in educational institutions worldwide. Teachers will also become more familiar with future directions in the practice of implementing extensive reading programs such as how to capitalize on the potential of the Internet to monitor and assess learners' progress in reading extensively. Thirdly, the paper provides directions for future research which we believe might fill critical gaps in our knowledge about ER.