This dissertation analyzes how medieval society understood the way gender characteristics were composed and balanced in a person by applying classical theories on biology, the humors, physiognomy, and astrology to medieval literary characters. These theories indicated that a tempering of masculine and feminine characteristics in a person led to a well-rounded and balanced individual and challenges the belief that medieval society had more rigid gender constructions. Through the application of these classical theories I first analyze male medieval literary characters that display hypermasculine characteristics extremely harmful to society, which lead to acts of rape and excessive violence, in the Reeve’s Tale, the French pastourelles, Sir Gawain and the Green Knight, and the Knight’s Tale. Effeminate characteristics in male characters help to illustrate the variation in types of gendered characteristics in Chaucer’s Absolon, the Squire, and Sir Thopas. Emasculated and feminized characters also offer ways masculinity and femininity are composed in Piers Plowman, Chaucer’s Tale of Melibee, Lancelot in Chretien’s Knight of the Cart, and Marie de France’s title character in Lanval; both latter narratives deal with male submission to a woman of higher status. Finally, I will argue that the rehabilitation of figures like the rapist knight in the Wife of Bath’s Tale was important to medieval society and reflective of a return to balance, and also how Chaucer’s Troilus illustrates what a balanced medieval literary character looks like. These examples help to provide a more accurate picture of how gendered characteristics were developed by medieval authors.