English-medium instruction (EMI) has been growing rapidly in higher education institutions worldwide as one of the chief language policy initiatives related to internationalisation. Acknowledging the centrality of teachers in EMI implementation and their role as micro-level actors in language policy and planning, this paper sets out to identify, compare and discuss expatriate and home teachers' beliefs concerning the benefits and challenges of EMI. To address these aims, an exploratory qualitative study was conducted at a Portuguese higher education institution. Data was collected through a structured questionnaire, which included closed and open-ended questions and submitted to statistical and content analysis. Results suggest that expatriate and home teachers have similar beliefs concerning the challenges of EMI. Still, regarding benefits, expatriate teachers seem to have a more 'educationalist' perspective of EMI, whereas home teachers seem to focus on its economic benefits. Implications of these findings for institutional language policy and planning are discussed.