This book provides the first extensive description of Texas Alsatian, a critically-endangered Texas German dialect, as spoken in Medina County in the 21st century. The dialect was brought to Texas in the 1840s by colonists recruited by French entrepreneur Henri Castro and has been preserved with minimal change for six generations. Texas Alsatian has maintained lexical, phonological, and morphosyntactic features which differentiate it from the prevalent standard-near varieties of Texas German. This study both describes its grammatical features and discusses extra-linguistic factors contributing to the dialect’s preservation or accelerating its decline, e.g., social, historical, political, and economic factors, and speaker attitudes and ideologies linked to cultural identity. The work’s multi-faceted approach makes its relevant to a broad range of scholars such as dialectologists, historical linguists, sociolinguists, ethnographers, and anthropologists interested in language variation and change, language and identity, immigrant dialects, and language maintenance and death.