Interest in formal Nuosu Yi language programmes has been waning in Liangshan, China, even though Nuosu Yi continues to be widely spoken among Yi residents. In this paper, we adopt Hornberger (2004. "The Continua of Biliteracy and the Bilingual Educator: Educational Linguistics in Practice." "International Journal of Bilingual Education and Bilingualism" 7 (3): 155-171.)'s continua of biliteracy and a translanguaging perspective to explore this phenomenon, and draw on a qualitative study of Yi students' and their teachers' language practices in three schools. Data include observations of Yi students' and teachers' spoken practices both in casual interactions and formal classroom instruction, and photos of their formal and informal written practices. Findings revealed a literacy-oracy divide in formal Nuosu Yi education: written Nuosu Yi was prioritised at school but was not found to be widely used in daily life. By contrast, spoken Nuosu Yi, which was drawn on frequently by students and teachers in informal interactions, was largely excluded at school due to a highly standardised and literacy-focused institutional setting. The continua of biliteracy and translanguaging allowed a nuanced investigation into different kinds of language practices at school, showing how the existing communicative repertoire of the students was not considered to be an asset in formal education.