Mandan is a Siouan language of North Dakota, near the geographic center of North America. There are no longer any first-language speakers after the last fluent speaker passed away in 2016. This grammar has been built from archival recordings of Mandan speakers from the 1960s through 2010, plus field work by the author undertaken between 2014 and 2016. The data from these various sources allowed for an in-depth description of the key aspects of the grammar of Mandan with special attention to the language's complex verbal and nominal morphology. This book also includes an overview of Mandan narrative structure, culminating with an interlinear gloss of a traditional Mandan narrative and its free translation into English. This grammar is written to be used by as general an audience as possible, including Mandan community members, scholars who wish to research Siouan languages, linguistic typologists, historical linguists, and other individuals who aim to conduct research on an indigenous language of North America.