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At the age of thirteen years old, a boy becomes obligated in performing mitzvot. 
- One should make a festive meal in honor of the occasion of his son turning 13 years old and entering the obligation of fulfilling mitzvot.  This meal is considered a Seudat Mitzvah. 
- The boy should learn Torah as much as possible on the day of his Bar Mitzvah. It is a nice practice to learn mishnayot.
- According to the majority of poskim, a boy becomes bar mitzvah from Tzet HaKochavim of the day he was born 13 years prior, and not at the time of the day when he was born.
- Upon the Bar Mitzvah of one’s son’s, the father should make the Bracha of Barach ShePotrani MeOnsho Shel Zeh, that he is no longer responsible for his child's deeds, without Shem UMalchut.  This beracha is typically recited when the son is called to the torah for the first time after concluding the beracha of his aliya.  Sephardim should also recite the bracha without shem umalchut.
- It is a good practice to have the bar mitzvah boy eat a new fruit or wear a new clothing in order to make a Shehechiyanu on the day that the boy becomes obligated in mitzvot. Upon reciting the Shehechiyanu, the boy should have in mind that he is accepting the obligation of fulfilling all the mitzvot. 
- Pirkei Avot 5:25
- Kaf Hachaim 222:11, Magen Avraham 222:4
- Kitzur Shulchan Aruch 61:8, Kaf Hachaim 225:11
- Kaf Hachaim 225:12
- Sefer Chinuch Yisrael (v. 2, p. 705). See further in the Bach O.C. 14, Magen Avraham 14, Shach, Sma, and Tumim C.M. 35.
- Rama 225:2, Mishna Brurah 225:8, BeYitzchak Yikrah 225:2 in name of Rav Shlomo Zalman Auerbach, and Piskei Teshuvot 225:5 conclude that one should make the Bracha without a Shem UMalchut.
- Kitzur Shulchan Aruch 61:8.
- Yalkut Yosef (Sovah Semachot v. 2 Bar Mitzvah no. 29)
- Kaf HaChaim 225:12 and Ben Ish Chai Reeh 17 say that a bar mitzvah boy should wear a new shirt or eat a new fruit on the day he becomes bar mitzvah'ed and have in mind with the Shehechiyanu that it should also cover his new acceptance of mitzvot.