This article explores how children in multilingual and transnational families mobilise their multiple and evolving linguistic repertoires creatively to assert their agency in language use and socialisation, and why these agency acts are conducive to successful maintenance of the so-called “home”, “community” or “minority” language. 12 hours of mealtime conversations within one Arabic and English-speaking multilingual family in the UK were recorded over a period of eight months. The family’s language practices unveil both their flexible language policy and the importance the family attaches to Arabic. The children in this family are fully aware of the language preferences of their parents and are capable of manipulating that knowledge and asserting their agency through their linguistic choices to achieve their interactional goals.