This article examines Appalachian English existentials, which employ they as the so-called “expletive” (e.g., They is a big creek yet). Given the morphological identity of expletive they with the third-person plural pronoun (e.g., They are happy), the question arises as to why the verb appears in the singular form in the existential despite the expletive's apparent plurality; this question arises in light of Cardinaletti (1997), who observes that cross-linguistically, Nominative Case-marked expletives trigger agreement. To explain the Appalachian contradiction, this work pursues the proposal that Appalachian expletive they is “weak,” lacking a value for its number feature. This allows us to maintain the idea that the Appalachian expletive does trigger agreement, despite appearances to the contrary. The article also explores (rarer) cases of Appalachian existentials with an apparently plural verb (e.g., They are another one down the street), and discusses three possible analyses of such grammars, where (1) the expletive might have a [+ plural] number feature, (2) the verb might actually be singular (despite appearances to the contrary), or (3) in the case of a plural postverbal subject (They have been some fellows...), the “associate” might raise at LF to agree with the verb.