Letters without Capitals: Texts and Practices in Kim Mun (Yao) Culture examines the writing culture of Kim Mun communities in Southeast Asia and China. The Kim Mun, who belong to the Yao ethnic group, are renowned for their Daoist religious practices and religious texts written in Chinese script. This work takes an unpublished Kim Mun letter that was composed in Laos and sent to Vietnam as its centrepiece. Through an analysis of the letter, one which uses ethnographic accounts of Kim Mun communities and studies of Kim Mun literary and religious texts, it demonstrates that writing is a cultural technology that primarily serves the purposes of the Kim Mun themselves, rather than being an artefact of historical and cultural relationships of dependency on external state institutions or religious constituencies. This has broad implications regarding our understanding of how writing can be adapted and deployed by minority communities on and beyond the margins of the state and of the underlying relationships between writing, identity and power.