The restrictions imposed by the Covid-19 pandemic since early 2020 have prompted a revolution in higher education as lecturers move to deliver their modules online. This shift is being followed by a growth in online resources for teachers, including a range of online courses providing 'quick tips' and techniques for online teaching. In our field of applied linguistics, the continuing need for support in transferring pedagogy online has been recognised by the British Association of Applied Linguistics (BAAL). In the long term, the impact of Covid-19 is likely to have transformative effects on the nature and delivery of higher education teaching and learning worldwide. This book steps back from the initial rush to help lecturers get online courses up and running and reflects on the theories and principles that underlie online teaching and learning, illustrating these with practical examples from applied linguistics courses. It invites readers to apply these new ideas to their own educational contexts. Written by a team of online learning experts based at The Open University, UK, the book covers a range of key issues including blended learning, online social presence, dialogic learning, critical digital literacies, and the role of English language studies as a vehicle for supporting students' development as language users in the digital age.