The article studies the sacramental teaching in Peter Lombard’s Sentences, a work that quickly became the principal theology text in the schools and universities from the High Middle Ages until the Counter Reformation. The study places Peter and the Sentences in the context of twelfth-century Europe’s renaissance of learning; it includes an analysis of Peter’s theology of the sacraments in general and, in particular, of penance and marriage, the most controversial sacraments of his era.