Canon law rules of marriage became the legal means for policing forbidden sex in Iceland during the Middle Ages. These rules were adapted to various needs: enforcing morality, encouraging adherence to Christian sexual norms, and managing inheritance practices and property rights. This chapter explores sex in Iceland in the fourteenth and fifteenth centuries by focusing on legal regulation, the archbishops’ and bishops’ statutes, and selected court cases. In all the Nordic countries the regulation of sexuality was highly influenced by canon law, but a study of sex in Iceland needs to be understood in relation to the special character of the society. It was highly literate, because of Christianity, but decentralized, with no towns and a distant royal administration. There had never been a strong executive authority in Iceland, and its absence seems to have encouraged widespread interest in documenting personal disputes and property rights. This makes Iceland special. Written documents and historical writing were mostly kept at the farms of leading families, for use in disputes over property rights in the local courts. This differs from more urbanized societies elsewhere in Europe.