This dissertation describes a newly-discovered variety of French, centered at Delisle, Mississippi. Mississippi Gulf Coast French (MGCF) is a Colonial survival, planted by Canadian and French settlers shortly after 1700, about fifty years before the Acadians arrived in Louisiana. Becoming part of Spanish West Florida in 1763, the coastal area in which Delisle is located was acquired by the United States after the Louisiana Purchase. The small francophone community persisted into the twentieth century as an enclave within the dominant English-speaking culture. The dialect's current state of demise was triggered when intergenerational transmission of MGCF was halted voluntarily by the first and only universally bilingual generation, those forced to learn English in school when compulsory education began in 1920. The last remaining members of that generation can still speak the language today. Sixteen speakers, most of them quite fluent, were recorded between 1994 and 1997, and on the basis of their speech the descriptive grammar focusing on the phonology and morphology was constructed Although MGCF ressembles in its phonology and lexicon the other North American descendants of seventeenth- and eighteenth-century European and Canadian French, it is structurally distinct, having almost abandoned the inherited noun gender system and largely replaced verbal inflection with analytic constructions. A detectable creole influence is consistent with the known presence of creole speakers around Delisle at least from the end of the eighteenth century, and the heavy English influence found is attributable to the bilingualism of the last speakers. The description presents almost the totality of the data collected, for future use in comparative, historical, typological, or other types of studies