This chapter shows that English as a lingua franca (ELF) and English for specific purposes (ESP) share common ground. ESP, and the research methodologies that support the ESP, can be seen to have made an important contribution to the understanding of what ELF is and how it is used, especially in English for specific business purposes, the concept of Business English as a lingua franca (BELF). The chapter starts with an overview of the key approaches, publications, and scholars that have characterized the ELF field, with particular reference to ESP. It also discusses ELF in different geographical locations, notably in Europe and in Asia, and briefly reviews ESP work done on specific types of ELF interactions in business and the professions. Large-scale projects like Vienna-Oxford International Corpus of English (VOICE) and English as an academic lingua franca (ELFA) will generate findings of interest to ESP scholars. © 2013 John Wiley & Sons, Inc.