The primary aim of this article is to put forward an argument that imagination plays a key role in whether and how members of transnational families individually and collectively maintain or relinquish their heritage languages and adopt other languages as part of their multilingual repertoires. Imagination is defi ned here as the vision of where and what one might be or become at some future point in time. We base our argument on linguistic ethnography over two decades with transnational families of Chinese ethnic origin in the UK.Families that seem to have kept their heritage languages and families that have given them up were invited to talk about where, what and how they would see themselves in ten years’ time, and a selection of them are subsequently interviewed and observed after the ten-year period. Their responses are analysed in terms of their constructed experiences, environments and visions of the future; their perceptions and imaginations of different places and cultures; key moments in re-evaluation, or re-imagining, that led to major behavioural changes;and self-evaluation of their imaginations. Particular attention is given to differences and tensions between the imaginations of individuals of the same families, as well as changes to the imaginations over time. Theoretical and methodological implications of studying imagination as a key factor for language maintenance and language shift, and for bilingualism research generally, are discussed.