Mosetén belongs to the small, unclassified language family Mosetenan and is spoken by roughly 800 people in the foothills of the Bolivian Andes and the adjoining lowland region. This grammar is the first accessible and comprehensive description of a Mosetenan language. It is based on the author's extensive fieldwork in Bolivia. The grammar covers the Phonology, Morphology, Syntax, and Discourse structure of Mosetén, and contains an index, three types of texts, as well as lists of morphemes in the appendix. It is aimed at linguists from all backgrounds and is of special interest to typologists, historical linguists, contact linguists, and South Americanists.