English for Academic Purposes (EAP) is an established domain of research, teaching, and assessment within additional/second language education. In this article we examine the conceptualisation of English that underpins much of its current thinking and pedagogic practice, and raise questions of validity and claims of ‘fit-for-purpose’. In particular we explore issues underpinning EAP assessment and argue that there is a need to reconceptualise the basis of the language model. We propose that given the complex and changing practices in academic communication, there is a good case for broadening the established understanding of Academic English to better reflect target language use. The principles and arguments underlying this discussion are relevant to assessment as well as to EAP more broadly.