“Secular” or private portraits of Christian individuals, married couples, and family groups appear in various media of visual art of the third and fourth centuries, surrounded by imagery expressing the religious commitments of those portrayed. After a discussion of the functions of portraits, a case study of the sarcophagus of Catervius and Severina illustrates the ways in which Christian patrons used portraits to construct and maintain a sense of identity in the changing society of Late Antiquity. Patrons adapted earlier forms of self-representation and incorporated elements of Christian iconography into their spousal or family portraits, including figures of Christ, crowns, and symbols such as the christogram and the cross. These new forms suggest distinctively Christian notions of marriage and family life. Comparing them with contemporaneous texts reveals ways that lay believers contributed, by visual means, to the Christianization of the Roman household during the faith’s formative period.