This paper will first discuss the role of English as a lingua franca from historical and socio-political perspectives; it will then review some relevant findings of research into actual interactions conducted in English as a lingua franca (ELF), before describing a study of ELF interactions. It will be argued that we need a new research agenda to adequately describe and explain the hitherto unknown global spread of one particular language, and the wide variety of functions, domains, situations and populations it has come to involve.