Post-colonial Hong Kong is an officially trilingual city with significant numbers of residents speaking English, Cantonese, Mandarin, or some combination of all three. Competency in these languages is promoted through educational policies and practices at all levels of schooling. Using concepts from the Deweyan framework of democracy and education, this article explores relational practices among bilingual co-teachers at a private, international early years programme in Hong Kong that emphasizes democratic philosophies of learning in their efforts to promote trilingualism. Findings point to co-teachers' interest in developing collaborative relationships, and prompting interest in additional language use through promotion of children's interests, along with tensions they experience as they grapple with instruction in multiple languages. Findings point to a need for more nuanced understandings of co-teaching dynamics in post-colonial multilingual learning contexts.