As English as a Medium of Instruction (EMI) continues to expand across the globe, there is a glaring absence of research on assessment. This article reviews the scarce literature to date and maps out a research agenda for the future. Drawing on Shohamy’s (2001, 2007) Critical Language Testing and McNamara et al.’s (2019) notions of “fair” and “just” language assessment, our reading of the literature to date is that it has revealed considerable complexities around implementing assessment in EMI contexts, with key questions centring not only on what and who to assess but also on how and why assessment should take place. In outlining a research agenda for the future, we suggest that one way of bypassing such challenges may be to carve out a greater role for assessment for learning in higher education. This could capitalize on – and raise stakeholders’ awareness of – bodies of knowledge that are well established within applied linguistics about the integral role of language in learning. Whilst we acknowledge challenges in securing institutional buy-in for putting this agenda into practice, we suggest that doing so could turn assessment challenges into opportunities and significantly enhance learning not only in EMI contexts but beyond.