This thesis questions the validity of the traditional approach to religious devotion in late- . i medieval England by broadening the chronological scope of investigation beyond Wyclif and the binary categories of orthodoxy and heresy that typify existing scholarly thought. The study provides an alternative means of interpreting Wycliffism and Lollardy, one that resists a teleological depiction of the heresy as a pre-cursor to the Reformation, and avoids over- emphasising the impact of Wycliffism on vernacular religious expression in the decades directly following Archbishop Arundel' s 1409 constitutions. The Introduction and first chapter examine a broader context for "Wycliffite" thought by considering the impact of the Fourth Lateran Council of 1215, and the subsequent pastoralia tradition that emerged. This examination establishes a framework for the study of late-medieval devotionalism, demonstrating the limitations of any model that simplifies the subject of religious worship and marginalises the series of alternative reformist narratives. The thesis suggests that Wycliffism and Lollardy was neither the sole nor the defining moment in late-medieval English religious history, and offers an alternative narrative independent of Wycliffism and LoIlardy that transcended the orthodoxy-heresy divide. The developments ofvemacular religious thought throughout the later Middle Ages are then traced using Langland's Piers Plowman, and subsequent chapters develop this theme. A new approach to devotion that frustrates traditional categorisation is explored by focusing on fifteenth-century texts from the "Piers Plowman tradition?', as well as a little-known sermon from the period, "Citizens of Saints". The last two chapters examine new modes of approved orthodoxy that emerged under the strategic leadership of Chic he le's Church and the Lancastrian monarchy, exploring the poetry of John Audelay, Thomas Hoccleve, and, to a lesser extent, John Lydgate, These demonstrate how the themes of orthodoxy, heresy and reform were negotiated in the literature of the post - Wyclif period.