The increase of internationalisation in Australian schools marks this as a significant teaching and learning experience for many teachers, specifically those in the secondary school. This case study of a secondary school investigated the concerns of teachers impacted by the implementation of an internationalisation policy. The study examined the teachers' responses to issues often associated with internationalisation in schools: pedagogy, curriculum and student inclusion. Four key concerns emerged in the data: (i) feelings of being ill-prepared; (ii) questions about curriculum enactment and student participation; (iii) the need for greater intercultural competence; and (iv) a lack of clarity about the relationship between language and literacy. The paper explores the implications of these concerns for teachers' practices and professional development as well as the place of international students in the school community.