The spread of English as the international lingua franca (ELF), like other aspects of globalization, calls for a reconsideration of conventional ways of thinking. This book argues that ELF needs to be understood as an entirely natural use of language in its own right and not as an erroneous version of native speaker English, and demonstrates how the ‘nonconformist’ formal features of ELF are functionally motivated by the dynamics of communicative interaction.