British and American English are both recognized as target varieties in institutionalized ELT settings. However, these are on an unequal footing when it comes to the impact they have on learners and the reactions they evoke among teachers. The present contribution discusses the problem of standards in English as a pluricentric language, the ideal of consistency in the use of one or the other, their representation in teaching materials and potential alternatives, as well as current linguistic research on varieties and their mutual influence. A quasi-experimental questionnaire study involving more than 400 nonnative teachers of English confirms the expectation that language professionals’ intuitions about acceptability are constrained by the variety they know best. Advocating a pedagogy that takes into account the role of English as an international lingua franca and concomitant variation, the study demonstrates that corpus literacy, widely taught in the linguistic components of teaching degrees, should also be routinely applied as a practical tool empowering teachers to transcend limitations resulting from their language contact biographies. The final sections point to the challenges of adopting an ELF-aware mindset in institutional settings and ways of overcoming these.