In the context of increasing linguistic and cultural diversity in Australian schools, it is important to consider the value of students' multilingual resources for learning. This paper reports on an ethnographic case study conducted in an Australian metropolitan secondary school where the student body represented more than 40 cultures and languages, yet where the broader structures of education were dominated by a monolingual orientation. The study draws data from student artefacts, student focus groups, a staff questionnaire, and staff interviews to reveal the ways in which multilingual students and their teachers construct and enact language policy at the classroom level. Key themes to emerge from the data included students' application of multilingual resources for individual and collaborative learning and the way multilingualism and related practices, such as translanguaging, were valued by students. Additionally, the data illustrated teachers' situated approaches ranging from a resistance towards multilingual practices, through to active construction of a multilingual classroom. Teachers' approaches which facilitated students' use of their own linguistic resources for learning, and how these approaches were negotiated within a context otherwise dominated by monolingual pedagogies will also be discussed in the paper.