Homilies and other texts of Christian instruction form an important part of Old Norse-Icelandic literature and give unparalleled insight into the religious worldview of medieval Icelanders and Norwegians. This chapter traces the development of this corpus, beginning with the first Norse encounters with Christian book culture in the conversion period and the earliest examples of book-production in Norway. It surveys evidence for the character, frequency and context of preaching in Iceland and Norway, including descriptions of sermons in such literary texts as Sverris saga. It discusses the most important repositories of sermons and homilies from this period, including the Icelandic Homily Book and Norwegian Homily Book. Finally, it considers Christian instruction and clerical training more broadly in the Old Norse world, looking at vernacular adaptations of theological primers and treatises translated from Latin, such as Elucidarius, Alcuin’s treatise on virtues and vices, and the Dialogues of Gregory the Great, and closing with discussion of the exempla (dœmisögur) associated with Jón Halldórsson, bishop of Skálholt.