Pius XI called the mutual perfection of spouses “the chief reason and purpose” of marriage, thereby opening the door for a consideration of the virtues spouses may seek in marriage. The article shows that for Augustine marriage is an instrumental good, serving the larger end of friendship, and that for Aquinas the bond of spouses—potentially a friendship of virtue—is the form, or defining quality, of marriage. The article concludes with a methodological coda on how and why a turn to virtue might be brought to the fore in a Catholic ethics of marriage.