The present research examined the Iranian in-service teachers' attitudes towards some principles of English as a lingua franca (henceforth ELF), particularly intelligibility and acceptability of their accent, the authority of non-native speakers to own the English language, and the legitimacy of English used by them. What makes the present research markedly different from the other language attitude studies is the context of research, namely Iran, an under-explored country in the literature concerning ELF. To amass the data, the researchers employed mixed-method design, using a questionnaire and follow-up semi-structured interviews. The results indicated that many a participant maintained contradictory and ambivalent attitudes towards ELF-related issues. Whilst the participants appeared to be inclined to agree with the principles pertaining to ELF, they did not display uniform attitudes about ELF-related issues in an in-depth analysis of the results. In fact, there appeared to be an underlying tendency towards the norms of native speakers of English among the participants. The results of the study may have implications for teacher trainers and ELF researchers.