Among contemporary Christians, the Roman Catholic Church recognizes as deuterocanonical several books that are consigned to the Old Testament Apocrypha by most Protestant bodies, whose canon conforms to that of the contemporary Hebrew Bible. There the books follow the order of the Palestinian Hebrew canon, which appears to have been adopted by c.a.d. 100, although most of the books had clearly received canonical status well before this time. The order is as follows: (1) the Torah or Law, the five books of the Pentateuch, i.e., Genesis, Exodus, Leviticus, Numbers, and Deuteronomy; (2) the Prophets, consisting of Joshua, Judges, First and Second Samuel, First and Second Kings, Isaiah, Jeremiah, Ezekiel, and the Twelve (or Minor) Prophets; (3) the Writings (Hagiographa), a heterogeneous group to which belong (a) Psalms, Proverbs, and Job, (b) the Scrolls (Megillot), consisting of the Song of Solomon (Song of Songs), Ruth, Lamentations, Ecclesiastes, and Esther, and (c) Daniel, Ezra, Nehemiah, and First and Second Chronicles.

The number of Old Testament books (not counting the Apocrypha) stands at 39; in the Hebrew Bible they are usually counted as 24. The discrepancy occurs because Ezra and Nehemiah are counted as one book, as are each of the following—First and Second Kings; First and Second Chronicles; and the 12 Prophets (Hosea through Malachi). Sometimes Judges and Ruth are also conflated, as are Jeremiah and Lamentations, making for 22 books, the number attested by Josephus (c.a.d. 36-a.d. 96).

The Old Testament was written in Hebrew, with a small portion in Aramaic (parts of the books of Daniel, Ezra, and Jeremiah). The text of the Hebrew Bible (called the Masoretic text, see Masora) had been standardized by the 10th cent. a.d., but the only existing Hebrew texts of biblical books before this time have been found at Qumran (see Dead Sea Scrolls). The origin of the Masoretic version is unknown.

The original Old Testament canon was the Septuagint, long used in the Greek-speaking church and still retained by the Orthodox churches. This Hellenistic Jewish translation originated with the translation of the Pentateuch in the mid-3d cent. b.c. Later translations were made from it or patterned after it. The canon of the Septuagint included the books of the later Hebrew canon, with the addition of several others, most of which were those now reckoned deuterocanonical by Roman Catholics and apocryphal by Protestants. Dispute over the canonicity of these books has its source in the Latin Bible, which found its official form in the Vulgate, the work of St. Jerome; this largely agreed with the list of books of the Septuagint, and the list and order of the Vulgate was the canon accepted by the Western Church of the Middle Ages.

At the Reformation, Protestant bodies withdrew recognition of the canonicity of those portions of the Old Testament that appeared in the Vulgate but not in the Masoretic canon, although the English church considered them (i.e., the deuterocanonical books) suitable for instruction and edification, but not for establishing or confirming doctrine. To set these books clearly apart, the translators who produced the Authorized Version (see Bible) assembled them in the Apocrypha as an appendix to the Old Testament. Thus the Protestant canon became exactly like the Masoretic, except that it retained the order of the books as they appeared in the Vulgate.

The critical study of the Old Testament is called higher criticism when dealing with literary-historical problems and lower criticism when dealing with questions of a purely textual nature. Chronology and authorship present great difficulties. Before c.1000 b.c. there is little likelihood of any outside source against which to check biblical chronology, but from the time of David it is possible to devise a chronology with some checks from nonbiblical sources, especially Assyrian and Babylonian inscriptions and records.

The Old Testament represents the confession of the people of Israel that God first became active in their affairs in the experience of their Hebrew pastoral ancestors. Through the centuries, he continued to protect, admonish, and guide their vulnerable descendants. Under Joshua they came into possession of the land of Canaan, which they inhabited, except for their exile (586-539 b.c.) in Babylon, until the Romans decimated the population of Jerusalem and burned the Temple in a.d. 70.

As it now stands, the Old Testament presents a history of once disparate tribal groups with different traditions as the story of one people. The whole nation in embryo went down into Egypt with the patriarch Jacob and his 12 sons, and was brought out from there under Moses' leadership some centuries later. Subsequently, the 12 tribes entered Canaan together and established a tribal league in the days of the Judges. It is more likely, however, that it was only in the days of the tribal league that the 12 tribes were first brought together.

In the 10th cent. b.c. the first of a series of editors collected materials from earlier traditional folkloric and historical records (i.e., both oral and written sources) to compose a narrative of the history of the Hebrews who now found themselves united under David and Solomon. Stemming from differing traditions originating among those living in what was later the northern kingdom of Israel and those in the southern kingdom of Judah, we can trace two dominant compilations, known as the E (preferring the epithet "Elohim" for God) and the J (preferring the epithet "Yahweh"), respectively. These were combined in Judah some time after the fall of the northern kingdom and are to be found inextricably associated in Genesis, Exodus, Numbers, Joshua, Judges, First and Second Samuel, and First and Second Kings. According to scholars, this combined JE narrative is the bulk of the earlier Old Testament.

The prophets began to confront Israel in the days of the divided monarchy, indicting the people for failure to heed the moral demand of God and for failing to protect the weak in society. Their warnings of doom came to pass as Israel fell before the imperial might of Assyria and Babylon. Faithful disciples of the prophets guarded their oracles, even supplementing them, long after their masters had passed from the scene.

To Deuteronomy, scholars assign a late 7th-century b.c. origin. Deuteronomy, the book of the law "found" in the Temple during the reign of Josiah, was written, scholars argue, for a specific purpose—to provide a written law for the people, and to authenticate the reforms Josiah had instigated. Deuteronomy gave rise to a historical work, called the Deuteronomic History, in which the older JE traditions were reworked in light of its theology. Leviticus, with its emphasis on priestly matters, probably reached its final form in the post-exilic era in the establishment of post-exilic Judaism. The books of Chronicles and of Ezra and Nehemiah provide a theological agenda for post-exilic Judaism, stressing Temple worship, ethnic purity, and adherence to the Mosaic law.