The book is addressed primarily to undergraduate students of Foreign Languages Departments as well as to postgraduates following courses in Applied Linguistics with a special focus on the learning and teaching of a second/foreign language. I also hope that it will be of interest to researchers, educationalists, and classroom practitioners who are concerned with the differential language development of their students. The book contains ten chapters grouped in two parts, and an epilogue. Its design would allow readers who like to read from beginning to end to do so, but each chapter stands alone as does each of the two parts, allowing those readers who are so disposed to read them separately and dip into when searching for specific information.