xxiv, 505 p. : ill. A print copy of this thesis is available through the UO Libraries. Search the library catalog for the location and call number. / Yakima Ichishkíin/Sahaptin is spoken in the Yakama Nation, located in the Pacific Northwest of the United States in what is now south central Washington State. The Ichishkíin and Nez Perce languages comprise the Sahaptian Family, classified as a member of the Plateau branch of Penutian. Ichishkíin speakers of a number of related dialects, including Yakima, live in the southern plateau region along Nch'iwána , the Columbia River, and its tributaries. The dialects are mutually intelligible, with slight differences in phonology, morphology, lexical items and orthographic representation. The fieldwork supporting this work was done in and around Toppenish, Washington with elders of the Yakama Nation. There are few fluent speakers, but there is great interest in language learning, teaching, and revitalization. Sahaptin is a synthetic to polysynthetic language with rich verbal morphology. The phonemic inventory is similar to other Pacific Northwest languages and consists of a large set of consonants and small set of vowels. Stops and affricates are voiceless with a plain and glottalized series. Grammatical relations are indicated with case-marking, verb agreement, and second position enclitics. Syntactic alignment is primarily nominative-accusative but there are also ergative and absolutive patterns. Word order is flexible, serving discourse/pragmatic functions. The language has a direct/inverse alternation in which the coding of participants depends on person and topicality hierarchies. Verbs are morphologically complex. A verb stem can be fully composed of bound morphemes that include lexical prefixes, motion prefixes, and stems that indicate a change of state or a location or direction. This dissertation is intended to support speech community members and scholars in language preservation and academic goals. The second and third chapters, covering the sound system and an overview of the grammar, constitute a condensed pedagogical grammar. Subsequent chapters offer more in-depth information about major aspects of the language Appendices include texts and classroom materials as well as a case study of a college-level Ichishkíin course that uses materials collected in a language documentation project as teaching tools. This dissertation includes previously published and unpublished co-authored material. / Committee in charge: Scott DeLancey, Chairperson, Linguistics; Eric Pederson, Member, Linguistics; Spike Gildea, Member, Linguistics; Janne Underriner, Member, Linguistics; Robert Davis, Outside Member, Romance Languages