This study of Aelred of Rievaulx’s understanding of marriage as a Christian state of life first considers his work in the context of earlier written souces and the debates about marriage in the twelfth-century schools; it then exposes Aelred’s thinking on the sacramentality of marriage, the position of woman in the marriage relationship, and the importance of marriage in relation to the common good, that is, the socioeconomic order. Much of Aelred’s thought remains applicable to Christian marriage today.