This is the first full-length study of the interrelation between sermons and vernacular religious drama in late medieval England. It investigates how these genres worked as media for public learning, how they combined this didactic aim with literary exigencies, and how the plays in particular acquired and reflected a position of authority. The interrelation between sermons and vernacular drama, formerly assumed relatively uncritically to be a close one, is addressed from a variety of angles, including historical connections, performative aspects, and the portrayal of the sacrament of penance. The analysis challenges the common assumption that Middle English religious drama is strongly influenced by contemporary sermons. Instead, the work demonstrates the subtly different purpose and content of these two genres and outlines the unique ways in which they operate within late medieval English devotional life.