Using a corpus of data drawn from naturally-occurring second language conversations, this book explores the role of idiomaticity in English as a native language, and its comparative role in English as a lingua franca. Through examining how idiomaticity enables first language learners to achieve a greater degree of fluency, the book explores why idiomatic language poses such a challenge for users of English as a lingua franca. The book puts forward a new definition of competence and fluency within the context of English as a lingua franca, concluding with an analysis of practical...