Pennsylvania Dutchified English, a little-studied German-influenced language variety spoken in south central Pennsylvania, is rapidly approaching extinction as speakers shift to the more standard regional variety of English. Not only are speakers using dialectal features less frequently, but the ways in which they use those features is also changing, thus altering what it means to “speak the dialect” and rendering the next generation of speakers incapable of acquiring it. In this context of inconsistency, a group of bidialectals have unexpectedly developed who are proficient in both Pennsylvania Dutchified English and the regional standard. Bidialectalism: An Unexpected Development in the Obsolescence of Pennsylvania Dutchified English investigates the shifts in use of various features by this dialect’s last generation of speakers and documents the use of those features in an ethnographic and statistical case study of a bidialectal individual. In this way, the volume thus contributes to the study of outcomes of dialect contact, language variety decline and death, and bidialectalism.