The Apostolic Fathers were core Christian theologians among the Church Fathers who lived in the 1st and 2nd centuries A.D., who are believed to have personally known some of the Twelve Apostles or to have been significantly influenced by them. Their writings, though widely circulated in Early Christianity, were not included in the canon of the New Testament. Many of the writings derive from the same time period and geographical location as other works of early Christian literature, which came to be part of the New Testament. Some of the writings found among the Apostolic Fathers appear to have been as highly regarded as some of the writings which became the New Testament. These writers include Clement of Rome, Ignatius, Polycarp, Hermas, Barnabas, Papias, and the anonymous authors of the Didachē (Teaching of the Twelve Apostles), Letter to Diognetus, Letter of Barnabas, and the Martyrdom of Polycarp. Not everything written by the Apostolic Fathers is considered to be equally valuable theologically, but taken as a whole, their writings are more valuable historically than any other Christian literature outside the New Testament. They provide a bridge between it and the more fully developed Christianity of the late 2nd century.

Reprint of the original, first published in 1882.