This is a project to produce a dictionary of the Koasati language to be a companion to the Principal Investigator's grammar of the language, completed in 1985. Three of the original native-speaker assistants in the compilation of the grammar will participate in creation of the dictionary. Koasati is an American Indian language of the Muskogean family, presently spoken in southwestern Louisiana and eastern Texas. The dictionary will contain five to six thousand entries based on present-day collection and also on material collected in the late nineteenth and early twentieth centuries. There will be a Koasati to English section and an English to Koasati section. Example sentences will be provided, and a brief sketch will preface the dictionary and explain grammatical terms and abbreviations. Verb paradigm and noun declensions will also be given. It is important at this time to collect reliable data on Muskogean languages not only because the number of fully competent speakers of the languages in this major group of North American Indian languages is falling, but also because of the recent publication of Joseph Greenberg's Language in the Americas, in which the relationship of the Muskogean languages to other North American Indian languages is controversial.