The corpus of Lightfoot's writings include essays on biblical and historical subject matter, commentaries on Pauline epistles, and studies on the "Apostolic Fathers". His sermons were posthumously published in four official volumes, and additionally in the Contemporary Pulpit Library series. At Durham he continued to work at his editions of the "Apostolic Fathers", and in 1885 published an edition of the "Epistles of Ignatius and Polycarp", collecting also materials for a second edition of "Clement of Rome", which was published after his death (1st ed., 1869). He defended the authenticity of the "Epistles of Ignatius".