There are some obvious difficulties in attempting to write about marital sex in the Middle Ages. For the most part, the texts that provide us with evidence about medieval social practices were written by clerics. These texts are necessarily problematic, in that they were written by clergy who should have been unmarried and celibate, and who were often either uneasy or hostile to all forms of sexual behaviour. They do not provide us with firsthand evidence of the experience of married people themselves. But the medieval Church's prolonged attempts to govern the sexual behaviour of the married laity nonetheless provides us with a great deal of evidence, about the nature of ecclesiastical intervention, and about actual practice.

The medieval Church's unease about sexual intercourse extended to marital as well as extramarital sex. Indeed, from a theoretical point of view, the position of extramarital intercourse was fairly straightforward for the Church, in that it was always sinful. The only things in question were the seriousness of the sin, and the measures that needed to be taken to combat it (this latter question, of course, providing significant practical difficulties for the Church). The role of marital intercourse was more complicated, for marriage was licit for Christians, and the married were obliged to accede to the sexual demands of their partners – to render the marital debt, as St Paul put it. But could they commit sin in doing so? Anxiety about marital intercourse, and the possibility of sin within it, troubled ecclesiastical commentators throughout the medieval period.