This paper examines expletive they, a form occasionally noted in the literature (especially on Appalachian English) but heretofore not analyzed. It examines phonological and syntactic patterns in which the form occurs and explores four hypotheses for its development. Two of these posit that expletive they reflects a phonological process of postvocalic /r/ loss from expletive there and a third that it is derived from pronominal they, which has an identical phonological shape. Historical citations support only a fourth possibility, which argues that expletive they can be traced to Ulster and ultimately to Scotland in the seventeenth century and has been in variation with expletive there for 400 years. The form is thus seen to have had a long and complex history in both the United States and the British Isles.