English as a lingua franca (ELF) has become ubiquitous in today's globalised, mobile and fast-changing world. It is clear that it will have an unprecedented impact not only on how we communicate but also on our understanding of language use and change. What exactly ELF brings to our life and to language theory is a question which requires an interdisciplinary take. This book gathers together leading scholars from world Englishes, typology, language history, cognitive linguistics, translation studies, multilingualism, sociolinguistics and ELF research itself to seek state-of-the-art answers. Chapters present original insights on language change, based on theoretical approaches and empirical studies, and provide clear examples of social, interactional and cognitive changes that ELF instigates. The picture which unfolds on the pages of this book is complex, dynamic and makes a convincing case for the importance of English as a lingua franca on language change at a global scale.