[Late Latin deuteronomium, from Greek deuteronomion, a second law (from (to) deuteronomion (touto) , Septuagint mistranslation of Hebrew mišnê hattôrâ hazzō't, a copy of this law) : deuteros, second + nomos, law.]

Fifth and last book of the Pentateuch, known in Hebrew as Devarim, "Words," from the opening phrase. The sages refer to it as Mishneh Torah (i.e., "the Repetition of the Torah," whence the Greek Deuteronomion---"Second Law"), as stated in 17:18, because most of this book is a review of the laws in the previous volumes: Exodus, Leviticus and Numbers. Following the Latin Vulgate, printed Hebrew Bibles divide Deuteronomy into 34 chapters and 955 verses. The Babylonian cycle of readings (which is followed today by all Jewish communities) divides the book into 11 pericopes (sedarot), but according to the Palestinian Triennial Cycle of Second Temple times, it contains 27 sections. Included in Deuteronomy are the Ten Commandments (5:6-18) and the first two paragraphs of the Shema (6:4-9, 11:13-21).

Traditionally, its contents were spoken by Moses during the last 37 days of his life, from 1 Shevat to 7 Adar, after which he died in the 40th year following the Exodus from Egypt.

Since Jewish tradition also maintains that Deuteronomy, like the other books of the Pentateuch, was dictated by God to Moses, this raises a well-known problem. Eight verses before the end of the book (34:5), it is stated that "Moses died there." How could Moses have written these words and the following verses? The Talmud gives two alternative answers: (a) the last eight verses were written by Joshua and not by Moses; (b) God dictated these last eight verses to Moses, in advance of his death, "and Moses wrote them down in tears."

The era in which Deuteronomy was written is a matter of dispute among scholars. Until a few decades ago, it was a commonly accepted view (as expounded by the 19th-century Bible critic Julius Wellhausen) that the volume, written by priests of the Deuteronomistic group, a short time before King Josiah discovered the scroll in 622 BCE, is Source D. The priests would have written the volume to persuade the king to centralize worship in the Temple in Jerusalem, which had not been the situation up until then. Other researchers, however, associate Deuteronomy with the period after the Babylonian exile; others again place it earlier, in the time of King Hezekiah (727-698 BCE); while still others hold that it was written even earlier, at a time when there was strong opposition to pagan worship in the Canaanite temples. According to this last view, the book was written during the period of the Judges or at an early stage of the monarchy. Seventh century BCE seems to be the most likely date for the compilation and editing of Deuteronomy in its present form.

Yeḥezkel Kaufmann, a modern Israeli Bible scholar, claims that the narrative material, the sections dealing with admonitions, and most of the statutes are very ancient, but that their influence was not great. Only during the period of Hezekiah and Josiah did these statutes become important.

The Jerusalem scholar Mosheh Ḥayyim Cassuto maintains that by far the greater part of Deuteronomy is extremely ancient, dating from even before David's time. Had the volume been written during the period of the monarchy, the author would certainly have attributed to Moses some hint that the ceremonial religious center of Israel would be Jerusalem, whereas Jerusalem is not mentioned at all.

In reply, defenders of the traditional view contend that (a) the book's underlying theme is not the centralization of worship but opposition to Idolatry. The most intensive struggle against idolatry took place during the time of Moses, when the monotheistic character of the nation was established. This struggle was particularly appropriate to the time after Israel's sinful attachment to Baal-Peor (Num. 25), when Moses wished to stress the danger posed by Canaanite ritual. (b) Parallels to most of the laws in the Book of the Covenant (Ex.20:19-23:33), repeated in this volume, are to be found in other codes of the Ancient Middle East (e.g., laws governing the monarchy and the appointment of judges), and these laws are therefore appropriate to the period. (c) The political background of Deuteronomy, such as the order to destroy the seven nations of Canaan, and Israel's relations with the Edomites and Egypt, is appropriate to the era of Moses and not to some other period. (d) Those passages dealing with contracts are appropriate to the laws of the Ancient Middle East, and can be compared to the Hittite vassal law. (e) Linguistically, there is nothing to disprove the hypothesis that this volume was set down at the time of Moses. A number of ceremonial expressions have parallels in Ugaritic literature; furthermore, the use of parallelism in poetry and prose as well as the change of person are characteristic not only of the Bible but of all the literature of the Ancient Middle East.

Scholars have tried to identify the circles from which the Book of Deuteronomy emanated. Some have pointed to the Levites, whose task it was to preach the Law; others have suggested political circles, notably court scribes. It has also beem suggested that the book's style inspired the editor of the Joshua-Kings bloc of the Former Prophets, representing a so-called Deuteronomic school of writing.