A Grammar of Nakoda (Assiniboine) is the first complete grammar of the Native American language Assiniboine, also known by the endonym Nakoda, a member of the Siouan language family. It addresses all major grammatical categories, including phonology, nouns, verbs, adverbs, enclitics, determiners, syntax, and kinship terminology. It also includes groundbreaking analysis of motion verbs of coming and going, demonstrating that such verbs compose a closed system that is consistent in varying degrees across all Siouan languages. Over the past century and a half, the classification of the Assiniboine language has suffered due to a complicated history regarding the Dakotan branch of the Siouan language family. Once spoken over a vast contiguous area of the northern plains, Assiniboine/Nakoda is used today among the Assiniboine people in and around Fort Belknap and Fort Peck in Montana and in five reserves in Saskatchewan. A Grammar of Nakoda (Assiniboine) establishes the singular basis of the language while also relating its unique features to other Great Plains American Indian languages.