In Rabbinic Judaism, the traditional method of determining Jewishness relies on tracing one's maternal line. According to , the recognition of someone as fully Jewish at birth requires them to have been born to a Jewish mother.Mishnah Kidushin 3:12; Shulchan Aruch, Even HaEzer 8:5 A person who is born to a non-Jewish mother and a Jewish father is regarded as () and will only be accepted as ethnically Jewish and not as religiously Jewish. Thus, being Jewish through the paternal line typically necessitates conversion to Judaism to validate one's identity as a Jew in the fullest sense.

Matrilineal descent is observed in Orthodox Judaism and Conservative Judaism, whereas Reform Judaism and Reconstructionist Judaism accept full Jewishness through either parent; Reform responsa, however, require an exclusively Jewish upbringing. Many scholars believe that patrilineal descent was observed by the ancient Israelites and that at some point Judaism switched to predominantly observing matrilineal descent. Orthodox Jews maintain that matrilineal descent determined Jewish status among the Israelites from the start while patrilineal descent was used to determine one's tribe. Patrilineal descent is observed by the Samaritans and in Karaite Judaism, which asserts that only the Hebrew Bible by itself—that is, disregarding the oral traditions of Rabbinic Judaism—is legally and religiously binding.

Contemporary Judaism The practice of matrilineal descent differs by denomination. Each denomination has protocols for conversion to Judaism for those who are not Jewish by birth. The State of Israel adheres to the Jewish law of matrilineal descent for matters which could affect Israeli family law.For the re-affirmation of matrilineal descent by the Chief Rabbinical Board of the State of Israel see Elberg, Rabbi S., September, 1984, HaPardes Rabbinical Journal, Hebrew, vol.59, Is.1, p. 21.

Conservative The Conservative Movement practices matrilineal descent. In 1986, the Conservative Movement's Rabbinical Assembly reiterated the commitment of the Conservative Movement to the practice of matrilineal descent. Furthermore, the movement stated that any rabbi who accepts the principle of patrilineal descent will be subject to expulsion from the Rabbinical Assembly. Still, the Conservative Movement affirmed that "sincere Jews by choice" should be warmly welcomed into the community and that "sensitivity should be shown to Jews who have intermarried and their families." The Conservative Judaism movement actively reaches out to intermarried families by offering them opportunities for Jewish growth and enrichment.

The Ratner Center for the Study of Conservative Judaism conducted a survey of 1,617 members of 27 Conservative congregations in the U.S. and Canada in 1995.Cohen, Steven M. “Chapter 1: Assessing the Vitality of Conservative Judaism in North America: Evidence from a Survey of Synagogue Members”. In Wertheimer, Jack (2000). Jews in the Center: Conservative Synagogues and Their Members. Rutgers University Press, p. 20. Steven M. Cohen who co-conducted this survey (Wertheimer, 5) notes that the sample under represents congregants from certain major metropolitan areas (the New York region being represented by only one congregation and the Toronto and Montreal regions having no representation), over represents socially upscale congregants, and under represents congregants under the age of thirty-five. (Wertheimer, 20) 69% of respondents to the Ratner Center survey agreed that they would regard personally as a Jew anyone who was raised Jewish—even if their mother was Gentile and their father was Jewish (Wertheimer, 59). In this same survey, 29% of respondents indicated that they attended Jewish religious services twice a month or more and 13% that they engage in the study of a Jewish text once a month or more (Wertheimer, 55–57).

Karaite The majority view in Karaite Judaism is that Jewish identity can only be transmitted by patrilineal descent.Karaite FAQs ; They argue that only patrilineal descent can transmit Jewish identity on the grounds that all descent in the Torah went according to the male line. Only someone who is patrilineally Jewish (someone whose father's father was Jewish) is regarded as a Jew by the Mo'eṣet HaḤakhamim, or the Karaite Council of Sages based in Israel.

Both Rabbinic and Karaite Jews lived in 12th century Egypt, and a number of marriage contracts between Karaite and Rabbinic individuals have been discovered in the Cairo Genizah. The Egyptian Karaites followed patrilineal descent,Yaron, Y., Joe Pessah, and Abraham Qanai. An Introduction to Karaite Judaism: History, Theology, Practice, and Culture. N.p.: Qirqisani Center, 2003. Print. but forbade marriage with non-Jews and also did not allow converts into their community.This ban was recently lifted by the Karaite Council of Sages. In effect then, 12th century Egyptian Karaites required that both parents be Jewish, but they referred to this requirement as patrilineal descent. Thus, marriages between Karaites and the Rabbinic community did not violate the Rabbinate requirement of matrilineality. However, these marriages came to a halt when Maimonides (who led the Rabbinate Jewish community in Egypt in the late 12th century) prohibited them for a separate reason: while he considered Karaites Jewish, he also considered them to potentially fall within the category of mamzerut, as their divorces were not conducted according to Rabbinate standards.

Orthodox Orthodox Judaism practices matrilineal descent.see Rabbi Moses Feinstein’s re-affirmation of matrilineal descent, Elberg, Rabbi S., September, 1984, HaPardes Rabbinical Journal, Hebrew, vol.59, Is.1, p. 21.Torat Menachem, Hitvaduyot, 5745, vol. 1, pages 133-136 Orthodox Judaism holds that anyone with a Jewish mother also has irrevocable Jewish status; that even were such a Jew to convert to another religion, that person would still be considered Jewish by Jewish Law.

Reconstructionist Reconstructionist Judaism was the first movement to adopt the idea of bilineal descent in 1968. According to Reconstructionist Judaism, children of one Jewish parent, regardless of gender, are considered Jewish if raised as Jews.

Reform In 1983, the Central Conference of American Rabbis of Reform Judaism passed a resolution waiving the need for formal conversion for anyone with at least one Jewish parent, provided that either (a) one is raised as a Jew, by Reform standards, or (b) one engages in an appropriate act of public identification, formalizing a practice that had been common in Reform synagogues for at least a generation. This 1983 resolution departed from the Reform Movement's previous position requiring formal conversion to Judaism for children without a Jewish mother.

The 1983 resolution of the American Reform movement has had a mixed reception in Reform Jewish communities outside of the United States. Most notably, the Israel Movement for Reform and Progressive Judaism has rejected patrilineal descent and requires formal conversion for anyone without a Jewish mother.Reform Judaism in Israel: Progress and Prospects As well, a joint Orthodox, Traditional, Conservative and Reform Bet Din formed in Denver, Colorado to promote uniform standards for conversion to Judaism was dissolved in 1983, due to that Reform resolution. However, in 2015 the majority of Britain's Assembly of Reform Rabbis voted in favor of a position paper proposing "that individuals who live a Jewish life, and who are patrilineally Jewish, can be welcomed into the Jewish community and confirmed as Jewish through an individual process." Britain's Assembly of Reform Rabbis stated that rabbis "would be able to take local decisions—ratified by the Beit Din—confirming Jewish status."

Other movements within the World Union for Progressive Judaism also adopted essentially the same position. These include: Liberal Judaism in England; Progressive Judaism in Australia; one congregation in Austria; some congregations in Eastern Europe. Note that Reform Judaism in Canada adopts a different position, similar to that of Conservative Judaism (though there may be an accelerated conversion process for the children of Jewish fathers).

Rabbinic outlook Orthodox Judaism maintains that the law of matrilineal descent in Judaism dates at least to the time of the covenant at Sinai (). This law was first codified in writing in the Mishna (),Yebamot 2:5; Kidushin 3:12 and later in the Mishneh Torah (c. 1170–1180 CE)Mishneh Torah, Laws of Forbidden Relationships, 15:4 and Shulchan Aruch (1563 CE), without mention of any dissenting opinion.Even HaEzer 8:5

According to one opinion, Jewish descent was patrilineal before the giving of the Torah, and only since then has been matrilineal.Sifra Vayikra 14:1;

The Talmud adduces the law of matrilineal descent from , which warns that as the consequence of intermarriage "he (the gentile father) will turn away your son (i.e., the child born to your Jewish daughter) from following Me". Since only "he" (a non-Jewish father) is mentioned and not "she" (a non-Jewish mother), the Talmud concludes that "your (grand)son who comes from an Israelite woman is called 'your son' (and warned about in the verse), while your (grand)son who comes from a foreign woman is not called 'your son'". Thus, Jewish descent is through the mother.Kiddushin 68a; see commentary of Ritva on Kiddushin 68a for a full explanation based on a close reading of the verse; see also Yebamot 17a and Numbers Rabba 19:3

The Matriarchs of Israel are considered the mothers of the Tribes of Israel; for those who adhere to Jewish Law, Israelite Nationhood or belonging to the Jewish People via descent exclusively follows the mother's line.; Gen. Raba 7, Rashi: Mishpachat Av Keruya Mishpacha … en mishpachat av keruya mishpacha …

Some Hasidic Jewish groups propose that matrilineality and matriarchy within Judaism are related to the metaphysical concept of the Jewish soul. Also, from the perspective of classical Jewish belief, the primary identity of all people follows the mother. Genesis 20:12, Rashi.

History Biblical period

Patriarchs and Matriarchs

The stories of the patriarchs and matriarchs in Genesis are generally compatible with matrilineal descent, if one makes the assumption that Abraham's extended family was "Jewish": Abraham fathered children with three wives or concubines: Sarah, Hagar, and Keturah, although it is likely that there were only two, as Hagar and Keturah appear to be different names used for the same person.Genesis 16:3,15, 25:1,2 According to Jewish tradition, Sarah was a member of Abraham's extended family,Sanhedrin 69b and her descendants became Jewish. The descendants of Hagar/Keturah were considered non-Jewish. Isaac had one wife (Rebecca, a member of Abraham's extended familyGenesis 24:10) and two sons, Jacob and Esau. Jacob's descendants became Jewish. Esau's descendants were non-Jewish: assuming matrilineality, this was a result of his wives being Hittite and Ishmaelite.Genesis 26:34,35, 28:9 Jacob had two wives (Leah and Rachel, members of Abraham's extended familyGenesis 29:10,12) and two concubines (Zilpah and Bilhah, who entered the family as maidservants of Leah and RachelGenesis 29:24,29). All of Jacob's children were considered Jewish. As for why Zilpah and Bilhah's children were considered Jewish despite their mothers having unspecified ancestry, rabbinic sources posit that Zilpah and Bilhah were actually the half-sisters of Leah and Rachel.Genesis Rabbati, Vayeze, p. 119; Yalkut Shimoni, Vayetze Remez 125; Targum Yonatan Genesis 29:24,29; Pirkei D'Rabi Eliezer chapt. 36 Alternatively, as Zilpah and Bilhah were maidservants, their children were considered to belong to their mistresses Leah and Rachel.Genesis 30:3; also, Leah and Rachel are the ones to name the sons born to Zilpah and Bilhah (Genesis 30:5-13)