In Geoffrey Chaucer’s The Canterbury Tales, key structural moments arise when a speaker shifts from rhyming heroic couplets to address the reader in prose, as well as in instances where prose is mentioned but not employed. These interruptions may seem like glosses explaining Chaucer’s intentions, yet they occur during the most contradictory moments of the frame narrative, making his aims particularly elusive. In Chaucer’s Problem of Prose, Stephen M. Yeager argues that the presence of prose in The Canterbury Tales exposes the complexities of poetic form, manuscript technology, and the media ecology of medieval clerical culture. The book asserts that Chaucer’s work is informed by his awareness of the significant role that Old English plays in early English monastic chronicles and cartularies, representing some of the earliest recorded uses of his chosen literary language. The book explores the surprising connections between the most striking depictions of racial otherness in The Canterbury Tales, the sections that engage with English monastic historiography, and the moments where Chaucer disrupts the narrative convention that dictates everyone in fourteenth-century England speaks in rhyming iambic pentameter couplets – either by writing in prose or discussing prose itself. Ultimately, Chaucer’s Problem of Prose examines how these moments reveal Chaucer’s anxieties about historical media and the central role of monastic historiography in documenting early English history.