This volume explores a highly topical applied linguistic issue: the spreading of English-medium courses and programmes in Higher Education. Hailed as a ticket to internationalisation, English is fast becoming a popular educational medium also at universities with a long-standing tradition of using the national languages for all academic purposes. By combining recent thinking into content and language integrated teaching and learning, discipline-specific language use and university language policies, the editors argue in the introduction that research can now offer principled insights into the practices of using English as an additional language for tertiary-level teaching and learning. By way of illustrating the diversity of such realities and their dynamic complexities, the individual contributions report on current empirical investigations taken from different European countries and discuss diverse aspects of English-medium tertiary education, such as classroom discourse, focus on form, English as a lingua franca, English for specific purposes, lecturer beliefs, language policies, as well as bi- and multilingualism.