ABSTRACT Lakhota is the most viable dialect of Sioux, spoken in the northern plains states and in central Canada. Although Sioux has been studied for nearly 150 years, there is no complete and consistent dictionary of any Siouan language. This project will use computer generated concordances to the text collections and extant dictionary materials to prepare the most complete and consistent dictionary possible. Eli James, a native speaker of Lakhota Sioux, will write the definitions and select or generate the examples and their translations, under the supervision of the Principal Investigators and with help from tribal elders as he needs it. The result will be orthographically consistent, will contain all the words in the documents which have been processed, and will be usable by both speakers and non-speakers of Lakhota. In particular, it will contain data for phonological and semantic studies of this rich language.