Drawing on the concept of family language policy (FLP), this paper reports on how four Chinese-English interlingual families maintain the minority language of Chinese with their preteenager children in Australia. The study takes an integrative approach to explore both parents' and children's perspectives on language development. While highlighting the increasing role that preteenagers play in the maintenance of a minor heritage language, the findings reveal that successful language maintenance in interlingual families is influenced by many other interacting factors, like language practice, attitude and support from each parent, language status, and the role of community schools. The study has clear implications for bilingual parenting and heritage language education in terms of the importance of a consistent FLP, preteenagers' self-efficacy, and actual language use in language maintenance.