This dissertation combines literary criticism of early modern drama with historical study of the English language to propose a new understanding of Jacobean city comedy. Extending recent interest in the materiality of culture, it argues that the English vernacular was a self-conscious aspect of their city for early modern Londoners, and reads three city comedies as documents of attitudes toward the vernacular in early modern London. City comedy's consistent subject is London and the “problem” of the changing, at times incoherent city. Central to this problem is the English vernacular, also experiencing flux due to great lexical expansion and calls for grammatical, lexical, and orthographic regulation. Questions of the language's adequacy to encompass the prodigious city are detectable in many period texts, and particularly in the comedies that distinguish Jacobean London. Ben Jonson's Epicoene and Bartholomew Fair, and Thomas Middleton's and Thomas Dekker's The Roaring Girl not only stage the city, but interrogate it as a landscape of language. An opening chapter surveys the period and asserts a distinct ethos of preoccupation with language, a combined exuberance and anxiety that succeeding chapters on each play will elaborate, Epicoene stages a city of talk centered on women as monstrous linguistic pretenders. Language posed as fashion and chatter is largely a problem of women and language in this play, whose conclusion offers little solution. The Roaring Girl's sentimentality contrasts with both the Jonson plays to suggest a diversity of responses in the generic project this study proposes. In the face of semiotic instability, The Roaring Girl offers a gendered fantasy of coherence. The cross-dressing “roaring girl,” Moll Cutpurse, becomes a benign force of social stability that renders other semiotic threats—sartorial freedom and the underworld language of cant—legible and docile. Finally, Bartholomew Fair stages an existential Fair-world in which anxieties about language and gender disappear because all language is a word-game and nothing matters. Reading these plays as iterations of a generic interrogation of language and London adds an historical and materialist depth to current understandings of Jonson, Middleton, and Dekker, and of city comedy's engagement with its urban setting.