Language immersion programs, which are a form of bilingual education, are shaped by multiple factors, including the specific characteristics of the region, the language, the community and the learners, as well as national and regional policies on language education. While the underdeveloped production skills of immersion students have been identified as the product of teacher-centred and controlled learning environments, it is not known what role background or heritage language students play in the Australian one-way immersion context, where their presence itself potentially enhances the speaking environment. This paper, based on a project on developing speaking strategies for a Japanese immersion program in Australia, argues that the speaking performance of students in immersion classes is also determined by other factors, such as peer interactions with background students, whose treatment in education systems in Australia remains ambiguous, reflecting the history of separation between foreign language education in schools and the maintenance of mother tongues in the community. By applying Critical Discourse Analysis (CDA), this paper analyses language policy and educational documents and discusses how the language performance of individual learners could be influenced not only by the curriculum but also by policy makers’ improved understanding of individual learners with diverse linguistic backgrounds within schools.