The Didache is the oldest surviving Christian church order and catechetical document. It provides instructions on Christian ethics (the 'Two Ways' of life and death), baptism, fasting, prayer, the Eucharist, and church organization. It reflects very early Jewish-Christian practice and may preserve traditions from the apostolic period.

The Shepherd of Hermas is one of the longest and most popular books in the early Church. It consists of visions, mandates (commandments), and parables (similitudes) delivered by an angelic figure in shepherd's dress. The main theme is the possibility of repentance for sins committed after baptism, a pressing question in the early Church.

First Clement is a letter from the church of Rome to the church of Corinth, written by Clement, the bishop of Rome. It addresses a schism in Corinth where younger members had deposed legitimate presbyters. Clement appeals to Old Testament examples, apostolic authority, and the need for proper order in the Church.

The Epistle of Barnabas is an early Christian treatise that uses allegorical interpretation to argue that the Old Testament, properly understood, always pointed to Christ. The author contends that Jews misunderstood their own scriptures by taking them literally. It includes the earliest version of the 'Two Ways' teaching also found in the Didache.

The Martyrdom of Polycarp is the earliest detailed account of a Christian martyrdom outside the New Testament. Written by eyewitnesses from the church of Smyrna, it describes the arrest, trial, and death of Bishop Polycarp at age 86. It established the pattern for later martyrology.

The Letter to Diognetus is an anonymous early Christian apology addressed to a pagan inquirer named Diognetus. It contains a beautiful description of Christians as the 'soul of the world,' living in the world but not belonging to it. It defends Christianity against paganism and Judaism while explaining Christian beliefs and ethics.

The Apostolic Tradition is one of the most important documents for understanding early Christian worship. It contains detailed instructions for the ordination of bishops, presbyters, and deacons, as well as baptismal liturgies, the Eucharistic prayer, and daily prayer practices. It claims to preserve apostolic practice.

The Protoevangelium of James narrates the birth and childhood of Mary, her betrothal to Joseph, and the birth of Jesus. It emphasizes Mary's perpetual virginity and miraculous conception. Though not canonical, it profoundly influenced Christian art, liturgy, and Marian doctrine.

The Wisdom of Solomon is a Jewish wisdom text written in Greek, probably in Alexandria. It personifies Wisdom as a divine figure, defends Jewish faith against Greek philosophy and Egyptian religion, and meditates on immortality and divine justice. It bridges Old Testament wisdom and New Testament Christology.

Sirach is a collection of ethical teachings, maxims, and hymns written by a Jerusalem sage. It covers topics from friendship and speech to liturgy and divine wisdom. The prologue by the author's grandson explains its translation from Hebrew to Greek for diaspora Jews.

Tobit tells the story of a pious Jew in exile whose prayers are answered through the angel Raphael. Parallel narratives follow Tobit in Nineveh (struck blind for his charity) and Sarah in Ecbatana (whose seven husbands were killed by a demon). Tobit's son Tobias, guided by Raphael, marries Sarah and heals his father.

1 Maccabees is a historical account of the Jewish revolt against Seleucid persecution (175-134 BC). It covers Antiochus IV's desecration of the Temple, the resistance led by the priest Mattathias and his sons (especially Judas Maccabeus), and the establishment of the Hasmonean dynasty.

2 Maccabees covers the period from the high priest Onias III to Judas Maccabeus' defeat of Nicanor (180-161 BC). Unlike the more sober 1 Maccabees, it emphasizes miraculous divine interventions, martyrdom theology, and resurrection of the dead. It is presented as an abridgment of a five-volume work by Jason of Cyrene.

The Book of Baruch is presented as written by Jeremiah's scribe during the Babylonian exile. It contains a confession of Israel's sins, a wisdom poem praising the Law, and prophetic consolation for Jerusalem. An appendix, the 'Letter of Jeremiah,' mocks idolatry.

1 Enoch is a collection of apocalyptic texts attributed to the antediluvian patriarch Enoch. It includes the 'Book of the Watchers' (fallen angels), astronomical writings, dream visions of history, the 'Parables of Enoch' (with the Son of Man figure), and the 'Epistle of Enoch.' It profoundly influenced Jewish and Christian apocalypticism.

The Gospel of Thomas is a collection of 114 sayings attributed to Jesus, many parallel to the canonical Gospels, others unique and enigmatic. Found at Nag Hammadi in 1945, it contains no narrative, miracles, or passion account. Its theology emphasizes hidden knowledge and the divine spark within.

The Didascalia is a church order from Syria providing instruction on Christian living, worship, and church organization. It addresses topics from the bishop's role to the treatment of sinners, widows, deacons, and the poor. It presents itself as the apostles' teaching at the Jerusalem Council.

The Acts of Paul and Thecla tells the story of a young woman of Iconium who heard Paul preach and abandoned her engagement to follow him. Despite persecution by her family and city, miraculous deliverances preserved her. She eventually received Paul's blessing to teach and baptized herself.

The Odes of Solomon are a collection of 42 early Christian hymns, the earliest Christian hymnbook. Written in Syriac (or possibly Greek), they express mystical union with Christ, baptismal themes, and joy in salvation. Their imagery is rich with light, water, and the Holy Spirit.