Making a celebratory meal and party:
The old tradition of celebrating a Bar Mitzvah but not a Bas Mitzvah: The Zohar states that the day of a boys Bar Mitzvah is similar to a wedding in terms of joy, and one must similarly rejoice on this day, just as one rejoices by a wedding. Accordingly, we find that throughout history a great celebratory feast, a Seudas Mitzvah, was made in honor of a boys Bar Mitzvah. The Poskim discuss the significance of this meal and rule that it has the status of a Seudas Mitzvah. The reason behind this great celebration is because the child has now joined the ranks of the Jewish people who are able to serve G-d and fulfill the Divine mission of creation. This is the true day of birth of a Jew. Likewise, it shows one’s excitement in serving Hashem. Some even write that making a celebratory meal on this day helps one merit a higher level of a Neshama. We find precedent for this celebration in the Talmudic statement regarding Rav Yosef, who was blind, that when he discovered that a blind person is obligated in Mitzvos, he made a celebratory meal in its honor. Certainly then, on the day that a person becomes obligated in Mitzvos, he should hold a celebration. Based on this reason, it would appear that there is no reason to differentiate between the celebration of a girl’s Bas Mitzvah or a boys Bar Mitzvah, as in both cases the child has now entered the ranks of the Jewish people, and it should be celebrated similar to a wedding. It thus should be a day of joy, not just for the girl and her parents, grandparents, and siblings, but for all the Jewish people. Nonetheless, until recent generations, the idea of a Bas Mitzvah celebration was unheard of. We find no discussion of it in Poskim, and have not received any tradition of its celebration from our ancestors, throughout our history. Thus, while the Bar Mitzvah celebration and feast was accustomed throughout the ages and talked about amongst the Poskim, a Bas Mitzvah was not celebrated in those times. Seemingly, this was avoided due to reasons of modesty, in keeping with the verse “Kol Kevuda Bas Melech Penima.” This all changed in the last couple of generations.
The start of the Bas Mitzvah celebrations: In the early 1900’s, the conservative, and later reform, movements initiated the Bas Mitzvah celebration and spread it to the populace, in order to motivate equality between men and women. Due to this, and other reasons, the Poskim of that generation vehemently opposed this change of tradition to start celebrating Bas Mitzvas. The Rebbe, and other Halachic authorities, took a unique approach to this subject, which today has become the accepted custom amongst orthodox Jewry. While a girl should make note, and have a celebratory occasion in honor of her Bas Mitzvah, it should not be performed in an over-extravagant manner, and is not to be done with the same publicity, as is done by Bar Mitzvas. It should preferably be held in the school, with her class, and her mother in attendance, and in all cases should remain small and modest. The day should be utilized to further strengthen the girl’s commitment to Torah and Mitzvos, and not for a vanity fair party. Obviously, one must take care that throughout the celebration, all the laws of modesty and Arayos discussed in Shulchan Aruch are abided by, such as not to have women singing in the presence of men. Many elementary schools limit the celebration of the Bas Mitzvah with specified guidelines that are meant to keep it modest, affordable, and in line with tradition.
One should hold a celebratory gathering in honor of her Bas Mitzvah. However, it should not be performed in an over-extravagant manner, and is not to be done with the same publicity, as is done by Bar Mitzvas. It should preferably be held in the school, with her class, and her mother in attendance, and in all cases should remain small and modest. One must take care that throughout the celebration, all the laws of modesty and Arayos discussed in Shulchan Aruch are abided by, such as not to have women singing in the presence of men.
Is a Bas Mitzvah celebratory meal considered a Seudas Mitzvah?
A Bas Mitzvah celebratory meal is not considered a Seudas Mitzvah, and is similar to the status of a birthday party.
May a Bas Mitzvah celebratory meal or Kiddush take place in the sanctuary of a Shul?
One may not hold a Bas Mitzvah celebratory meal in the sanctuary of a shul.However, one may hold a celebratory Kiddush in the shul after Shabbos Davening, if it is common to do so in that Shul for other occasions.
May one schedule a public Bas Mitzvah celebration for Friday night or Shabbos?
As stated above, the Rebbe opposed public Bas Mitzvah celebrations. Nonetheless, if this has become the custom, it is best not to schedule the celebration of a Bas Mitzvah for Shabbos, in order to avoid desecration of Shabbos from occurring.
 Brought in M”A 225:4 in name of Likkutim 29
 M”A 225:4; Rashal Bava Kama 7:37 based on Rav Yosef Keddushin 31; Degul Merivava Y.D. 391:2 in name of Rashal
 Yechidus 22nd Kisleiv 5746
 Yechidus 16th Tamuz 5747
 Kaf Hachaim 225:11
 Keddushin 31
 See Rashal ibid; Machatizs Hashekel 225:4
 Igros Moshe O.C. 2:97; Rebbe in Sefer Hasichos 5748 1:332 footnote 21; See P”M 225 A”A 5 regarding Birchas Shpotrani who asks why it is not also said by a Bas Mitzvah.
 Yechidus night of 15th of Tamuz 5745
 Ketzos Hashulchan vol. 9 p. 3; See Kaf Hachaim 225:11 that “even though we do not make a Seuda”
 See Ketzos Hashulchan vol. 9 p. 3; See Igros Moshe O.C. 2:97 who leaves this matter in question, although suggests that perhaps the purpose of the celebration is to publicize the child’s ability to join a Minyan, and is thus not relevant to woman.
 There were occasional attempts to recognize a girl’s coming of age in eastern Europe in the 19th and 20th centuries, the former in Warsaw (1843) and the latter in Lemberg (1902). [See Marcus, Ivan G. (2004). The Jewish Life Cycle: Rites of Passage from Biblical to Modern Times.] The American rabbi Mordecai M. Kaplan, held the first public celebration of a bat mitzvah in the United States, for his daughter Judith, on March 18, 1922, at the Society for the Advancement of Judaism, his synagogue in New York City. Change came gradually. As late as the 1930’s, despite Judith Kaplan’s pathbreaking example, only a handful of Conservative synagogues had adopted bat mitzvah. By 1948, however, one-third of Conservative congregations conducted them and, by the 1960s, the ceremony became the norm within Conservatism. The earliest American bat mitzvot were, ritually, not quite the same as bar mitzvot. They were usually held on Friday nights, when the Torah is not read or, if held on Saturday morning like Judith Kaplan’s, the bat mitzvah girl would read from a printed Chumash, or book containing the Bible, rather than from the Torah scroll itself. The first recorded bat mitzvah at a Reform congregation occurred in 1931 but, as with the Conservative movement, the ritual did not catch on right away. By the 1950’s, only one third of Reform congregations conducted them. Since the 1960s, as Reform has placed increasing emphasis on traditional rituals, bat mitzvah has grown to near universality in that movement’s congregations. A number of modern Orthodox congregations have now adopted some form of bat mitzvah as well. Bat mitzvah, an innovation in 1922, is now an American Jewish institution. [Sources: American Jewish Historical Society]
 Zekan Ahron 1:6 [vehemently opposed it and states it transgresses grave prohibitions]; Ketzos Hashulchan vol. 9 p. 3 opposed even a family gathering; Igros Moshe O.C. 1:104 [does not go as far as to say that it is forbidden, but states that it does not involve a Mitzvah and is better off not done]; O.C. 2:97; O.C. 4:36; Otzros Yerushalayim 129 p. 461-463
 The reason: First off, if our forefathers did not follow this custom, certainly there is a reason for it and we should not start a new custom. [Ketzos Hashulchan vol. 9 p. 3] Furthermore, some Poskim rule that it transgresses Bechukoseihem Lo Seileichu, as it was initiated by the reform movement who are heretics and deny the foundations of our faith. [Zekan Ahron ibid] Others say that it has no meaning and purpose in Kedusha, and hence cannot be considered a Seudas Mitzvah, and is simply like a birthday party. [Igros Moshe ibid] Likewise, many people use it today to perform parties in which Torah laws are transgressed, such as mixed singing, dancing, immodest dress and behavior, and hence even Bar Mitzvos should be nullified for this reason. [Igros Moshe O.C. 1:104; O.C. 4:36]
 Seridei Eish 3:93; Yechaveh Daas 2:69
 See Midrash Sechel Tov Vayeishev 20; Ginzei Yosef 4; Ben Ish Chaiy Rei 17; Hisvadyus 1988 vol. 3 p. 152  that on the day of the birthday one is to celebrate with family and friends and have a festive Chassidic gathering, which is a Simcha Shel Mitzvah, giving praise and thanks to the Creator.
 See Igros Kodesh 17:237 “Regarding the custom of Bas Mitzvah celebrations which has lately spread also to the religious world, to the point that it is almost impossible to abolish it”; Rav Hillel Pezner received from the Rebbe in Yechidus, printed in “Bas Yud Beis Lemitzvos” chapter 3 that it should not be done similar to a Bar Mitzvah, but rather as a small and modest celebration; Yalkut Bar Mitzvah p. 129 brings that the Rebbe told the author that one is not to make a public celebration, unless this has become the norm, in which case he should do so in a diminished fashion; In a reply to Hanhalas Beis Rivka, the Rebbe stated that it should be done either as a Mesibas Shabbos or as a Melaveh Malka.
 Ketzos Hashulchan vol. 9 p. 3
 See Igros Kodesh 17:237
 Igros Moshe O.C. 1:104; Seridei Eish 3:93
 Igros Moshe O.C. 1:104; O.C. 4:36; Seridei Eish 3:93
 The reason: As it is not a Seudas Mitzvah, but rather a Seudas Reshus, for which even a Tnaiy upon building the Shul does not suffice. [ibid]
 Igros Moshe O.C. 4:36
 Igros Kodesh 17:237