(Almost) everyone here spoke Ban Khor Sign Language—Until they started using TSL: Language shift and endangerment of a Thai village sign language

•Village sign languages and speech/sign communities are rare and endangered.•Speech/sign communities expand and enrich speech community theory.•Ban Khor, Thailand is home to a village sign language and speech/sign community.•BKSL began as a home sign system but rapidly became a village sign language isolate.•Ban Khor Sign Language is now endangered by Thai Sign Language.

Found only in face-to-face communities with distinctive socioeconomic and demographic profiles that include numerous deaf residents, ‘village sign languages’ correlate with special ‘speech/sign communities,’ wherein widespread deafness is successfully communicatively managed because hearing villagers routinely acquire and use the local sign language. This language variety is as unusual as its sociolinguistic environment is fragile. Charting the life course of a contemporary village sign language and speech/sign community in Thailand, this article examines the causes and consequences of the emergence, expansion, and endangerment of Ban Khor Sign Language and its speech/sign community.