The Ecclesiastical History (Ancient Greek: Ἐκκλησιαστικὴ Ἱστορία, Ekklēsiastikḕ Historía; Latin: Historia Ecclesiastica), also known as The History of the Church and The Church History, is a 4th-century chronological account of the development of Early Christianity from the 1st century to the 4th century, composed by Eusebius, the bishop of Caesarea. It was written in Koine Greek and survives also in Latin, Syriac, and Armenian manuscripts.

The result was the first full-length narrative of the world history written from a Christian point of view. summarizes Eusebius's influence on historiography. According to Paul Maier, Herodotus was the father of history and Eusebius of Caesarea is the father of ecclesiastical history. In the early 5th century, two advocates in Constantinople, Socrates Scholasticus and Sozomen, and a bishop, Theodoret of Cyrrhus, Syria, wrote continuations of Eusebius's account, establishing the convention of continuators that would determine to a great extent the way history was written for the next thousand years. Eusebius's Chronicle, which attempted to lay out a comparative timeline of pagan and Old Testament history, set the model for the other historiographical genre, the medieval chronicle or universal history.

Eusebius had access to the Theological Library of Caesarea and made use of many ecclesiastical monuments and documents, acts of the martyrs, letters, extracts from earlier Christian writings, lists of bishops, and similar sources, often quoting the originals at great length so that his work contains materials not elsewhere preserved.

It is therefore of historical value, though it pretends neither to completeness nor to the observance of due proportion in the treatment of the subject-matter. Nor does it present in a connected and systematic way the history of the early Christian Church. It is to no small extent a vindication of the Christian religion, though the author did not primarily intend it as such. Eusebius has been often accused of intentional falsification of the truth ^{[citation needed]}. Other scholars, while admitting that his judging of persons or facts is not entirely unbiased, push back on claims of intentional fabrication as "quite unjust."

Eusebius attempted according to his own declaration (I.i.1) to present the history of the Church from the apostles to his own time, with special regard to the following points:

He grouped his material according to the reigns of the emperors, presenting it as he found it in his sources. The contents are as follows:

Andrew Louth has argued that the Ecclesiastical History was first published in 313. In its present form, the work was brought to a conclusion before the death of Crispus (July 326), and, since book x is dedicated to Paulinus, Archbishop of Tyre, who died before 325, at the end of 323 or in 324. This work required the most comprehensive preparatory studies, and it must have occupied him for years. His collection of martyrdoms of the older period may have been one of these preparatory studies.

Eusebius blames the calamities which befell the Jewish nation on the Jews' role in the death of Jesus. This quote has been used to attack both Jews and Christians (see Antisemitism in Christianity).