A focus on spiritual friendship through the lens of Medieval Christian writings frames this chapter. Despite the lack of the trope of friendship in the New Testament of the Bible, and an emphasis on the love of Christ, church leaders throughout the Middle Ages made reference to friendship with God, and to friendships between spiritual brothers and sis`ters. The writings on friendship by the three most prominent in this field, Saint Augustine, Saint Aelred of Riveaulx and Saint Thomas Aquinas, are considered first. This is followed by a review of other writers of the period from the fourth to the fourteenth centuries, ranging from St. Katherine of Alexandria (c. 232–c. 305) to Margery of Kempe (1373–c. 1438). A discussion follows that explores male-male friendship, as for example between St. Basil the Great, Archbishop of Caesarea, and St. Gregory of Nazianzus, Archbishop of Constantinople, in the fourth century AD; female-male friendship, including the famous relationship between Heloise of Argenteuil, later Abbess of Paraclete, and Pierre Abelard, her former tutor and French philosopher, in the eleventh and twelfth centuries; and female-female friendship, as between St. Merchtild of Hackeborn and St. Gertrude the Great, who led the convent of Helfta in Germany in the thirteenth century. A summary that includes the influences of the Greek and Roman philosophers on Medieval scholars concludes the chapter.