Host and international students evolve side-by side within the expanding internationalization of higher education. This study takes the complementary perspective of analysing 1,900 host and international students' experiences at a high-ranking research university in France. We analyse and compare the mobility, language practices and practices related to university life of these two populations interacting within a common higher education setting. Despite common needs of language skills for professional needs, our results demonstrate significant differences in their declared concerns and practices, suggesting that each population remains largely within their diverging 'comfort zones'. We find a lack of social interaction between host and international students, producing a two-way deficit, where many host students miss an opportunity to benefit from practicing foreign languages and discovering new socio-cultural perspectives, while many international students miss an opportunity for local social and institutional support, known to reduce stress. We conclude with suggestions for adapting university policies to remedy this deficiency.