Education via a minoritised language is broadly considered as a critical element of language revitalisation initiatives. This paper proposes findings from a comparative study of teacher education programmes adopted in Wales, New Zealand, Catalonia, and the Basque Autonomous Community, to prepare teachers to teach via the media of Welsh, Māori, Catalan, and Basque respectively. The inquiry was conducted to inform new professional development initiatives in Scotland, designed to allow qualified teachers to transfer from English-medium to Gaelic-medium education.