This Element focuses on English-Medium instruction (EMI), an educational approach that is spreading widely and rapidly in higher education institutions throughout the world because it is regarded as a lynchpin of the internationalisation process. The main aim of the Element is to provide critical insights into EMI implementation and the results obtained so far in diverse university contexts. After defining EMI and analysing the rapid extension it has experienced, the volume tackles issues such as stakeholders' views on how EMI programmes are being implemented, the impact of teaching and learning both content and language in a foreign language, translanguaging practices in English-medium lectures, and how assessment has hitherto been addressed. Each section aims to bring to light new avenues for research. The Element wraps up with a description of the many challenges ahead.