It is often assumed that medieval laypeople did not understand or follow the Latin church services they routinely attended. This thesis re-examines the role of the laity in medieval devotions and argues that careful attention to manuscripts reveals multi-layered levels of understanding and approaches to doctrine and the liturgy across lay and religious communities. It investigates the inter-relationship of literary text and its placement within the material manuscript, closely considering the ways in which word and image inform and illuminate each other. Sometimes these devotions take the form of Passion prayers adapted from the liturgy, such as the understudied vernacular translations of the early fourteenth-century hymn to the cross, Patris Sapiencia, and Anglo-Norman and English Mass Prayers. This thesis demonstrates that the placement of these prayers in medieval books reveals that they were intended actively to be read by the laity as they followed the vernacular alongside the Latin of medieval services. Other devotions take the form of lyric verse for private use. Placing these devotions in their proper contexts in laypeople’s medieval books reveals their theological depth, especially regarding lay understanding of and response to the doctrine of the atonement.