Yuki and the other Northern Yukian languages, Huchnom and Coast Yuki, were spoken until recently in Mendocino County in Northern California. This dissertation is a grammar of Yuki based primarily on spoken narratives recorded in the first decade of the twentieth century, so it provides a description of the Yuki language as it was spoken at that time. The narratives were provided by Yuki speaker Ralph Moore and recorded by Alfred Kroeber. Supplemental examples are drawn from the large base of elicited material by various other researchers over the course of the twentieth century. Where possible, information is also included on Huchnom and Coast Yuki, which together with Yuki Proper constitute the Northern Yukian languages. In recent years it has become increasingly apparent that complex structures can be borrowed through language contact. Northern California, where Yuki was spoken, is well known as a strong linguistic area, in which neighboring language have had strong effects on each other. This description of Yuki is thus set in the context of its contact languages, in order to show the types of features it shares with its neighbors. Several glossed, analyzed, and translated Yuki narratives are included in the appendix. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]