* Note for those in Eretz Yisrael: Those who keep only one day of Yom Tov [i.e. residents of Eretz Yisrael] fulfil the customs of Simchas Torah on Shemini Atzeres. See Chapter ?? for the fulld eatils of the laws and customs of Simchas Torah.
1. Is Shemini Atzeres defined as a Chag [within the prayer liturgy]?
Some Poskim rule that Shemini Atzeres is not defined as a Chag/festival in any source in scripture, and hence in the prayer liturgy one is not to say “Shemini Atzeres Hachag Hazeh” but rather simply “Yom Shmini Atzeres.” Other Poskim, however, rule that it is defined as a Chag and thus one is to say in the prayer liturgy “Vatiten Lanu Es Yom Shemini Chag HaAtzeres Hazeh”. Practically, the final ruling follows the latter opinion to call it a Chag in the prayer liturgy.
Sparks of Chassidus
Receive Divine service for entire year:
On the day of Shemini Atzeres the entire Jewish people receive the Divine blessing and assistance for their learning of Torah and service of Hashem of the entire coming year. Just as we begin mentioning rain on Shemini Atzeres, so too we receive the spiritual rain, which is the blessing in our Divine service.
Draws down the light of the High Holidays:
During the High Holidays, we draw down revelations of G-dliness for the coming year. This is likewise drawn down during the festival of Shemini Atzeres. The only difference is in regarding the method. That which was drawn down during the High Holidays in a mode of awe and reverence is drawn down again on Sukkos, with joy and exuberance. This particularly applies during Shemini Atzeres.
It is the custom of the Jewish people – and hence it is Torah – to rejoice on Shemini Atzeres and Simchas Torah more than at Simchas Beis HaShoevah, and more than on a usual Yom-Tov.
Dancing draws down all the blessings: 
The Rebbe Rayatz stated in the name of his father, the Rebbe Rashab, that the forty-eight hours of Shemini Atzeres and Simchas Torah should be dearly cherished, for at each moment one can draw bucketsful and barrelsful of treasures both material and spiritual, and this is accomplished through dancing.
2. Erev Shmini Atzeres:
A. Eating a meal on Erev Shemini Atzeres:
See Chapter 4 Halacha 10!
B. Taking down the Sukkah:
See Chapter 4 Halacha 11!
C. Shehechiyanu by candle lighting:
The blessing of Shehechiyanu is recited during candle lighting of Shemini Atzeres.
3. Eating and sleeping in the Sukkah?
In the Diaspora, one must eat in the Sukkah on Shemini Atzeres, by both night and day.
What is one to required to eat in the Sukkah on Shemini Atzeres? One is obligated to eat the bread meals and 55 grams of Mezonos within the Sukkah on Shmini Atzeres, just as is required on Sukkos itself. Regarding other foods, such as fruits, vegetables, beverages, and the like, from the letter of the law one is not required to eat them in the Sukkah, just as is the law on Sukkos itself. Furthermore, some Poskim rule that one is to specifically not eat these foods in the Sukkah in order to emphasize its lack of Biblcial status. Other Poskim, however, rule that those are metcculous throughout Sukkos to eat even fruits and drink water in the Sukkah may continue to do so as well on Shemini Atzeres. Practically, the final ruling follows the latter opinion. The Chabad custom follows the latter opinion to be meticulous even on Shemini Atzeres to recite Kiddush and eat and drink everything in the sukkah, both by night and by day.
Is one to sleep in the Sukkah on Shemini Atzeres? Some Poskim rule that one is not to sleep in the Sukkah on Shemini Atzeres. Other Poskim, however, rule that one is obligated to sleep in it on Shemini Atzeres, just as one is obligated to eat in it. Practically, some have the custom to sleep in the Sukkah even on Shemini Atzeres, while others do not. The Chabad custom is not to do so.
B. Eretz Yisrael:
One does not eat or sleep in the Sukkah in Eretz Yisrael on Shemini Atzeres. Furthermore, it is even forbidden to eat/sleep in the Sukkah on Shemini Atzeres unless one makes some form of recognition that shows that the Sukkah no longer maintains its holiness and Mitzvah. For example, in Eretz Yisrael where Erev Shemini Atzeres is Hoshana Raba, one is to remove a 4×4 Tefach area of Sechach from the roofing to show that he is not intending to saty in it for the sake of the Mitzvah. See Chapter 6 Halacha 2!
4. The Maariv Davening:
A. The prayers:
The Maariv prayer includes the regular Yom Tov Maariv and Shemoneh Esrei which is then followed by Kaddish Shaleim. In Chabad Shul’s the custom is to now hold a Farbrengen. This is then followed by Ata Hareisa three times, Hakafos, and Aleinu.
What is the law if one accidently said “Beyom Chag Hassukos Hazeh in Shemoneh Esrei or Kiddush?
Diaspora: It is an ancient custom to perform Hakafos also on Shemini Atzeres just as on Simchas Torah, and to circle the Bima on the night of Shemini Atzeres seven Hakafos with the Sifrei Torah in great joy and dancing. Even after completing the Hakafos in one Shul, if one arrives to another Shul who has yet to complete the dancing, he is to join them in the dancing and rejoicing. [Practically, the Chabad custom is to perform seven Hakafos on the night of Shemini Atzeres, just as is performed on the night of Simchas Torah. See Chapter 6 Halacha 7 for all the details regaridng Hakafos! Other communities do not perform Hakafos on the night of Shemini Atzeres.]
Eretz Yisrael: In Eretz Yisrael, where Shemini Atzeres and Simchas Torah coincide, the Simchas Torah Hakafos takes place during Maariv prayers.
5. The meal:
Kiddush in Eretz Yisrael: In Eretz Yisrael that Shemini Atzeres and Simchas Torah coincide, it is customary for all to say Kiddush.
Not to dip the bread in honey: On Shemini Atzeres and Simchas Torah one does not dip the bread of Hamotzi in honey.
6. Avoiding Tashmish:
One is to avoid marital relations on Shemini Atzeres.
Night of Mikveh: If the night of Mikveh falls on Shemini Atzeres, one is to have marital relations. [One who refrains from doing so is considered as if he is performing a Mitzvah as a result of an Aveira.]
Strong desire: Those who feel a strong desire which may prove difficult to withhold are better to have intercourse than to come to doing a sin.
A. Completing Shacharis before midday:
There were times [in the minyan of the Previous Rebbe] when a point was made of completing Shacharis on Shemini Atzeres before midday.
Israel: In Israel, where Shemini Atzeres and Simchas Torah coincide, the Simchas Torah Hakafos takes place during Shacharis prayers. Diaspora: Hakafos is not done on Shemini Atzeres day. This applies even accoridng to those accustomed to performing Hakafos on the night of Shemini Atzeres.
C. Torah Reading:
Diaspora: Two scrolls are removed from the ark. The portion of “Kol Bechor” from Parshas Re’ah is read from the first Torah scroll. Five Aliyos are called up to read from the first Torah scroll and if Shemini Atzeres falls on Shabbos, then seven Aliyos are called up. Maftir is read from the second Torah scroll, from the portion of “Bayom Hashmini Atzeres.” The Haftorah is read from Melachim I 8:54-66, from Vayehi Kechalos Shlomo until uleYisrael amo.
Israel: In Israel, where Shemini Atzeres and Simchas Torah coincide, three Torah scrolls are removed from the ark. From the first Torah scroll one reads from Vezos Habrach until the end of the Torah. From the second Torah scroll one reads from Bereishis until the words “Asher Bara Elokim Lasos.” From the third Torah scroll Maftir is read from “Ubayom Hashemini Atzeres.” See Chapter 6 Halacha 10B!
No Minyan: Yizkor may be recited even if a Minyan is not present.
Candle: It is not the Chabad custom to light a candle for Yizkor. The Rebbe and Rebbe Rayatz did not light Yizkor candles.
Aliyah: It is not the custom to be particular to receive an Aliyah on the day of Yizkor.
How to mention the name: One is to mention the name of the Niftar together with the name of his mother during Yizkor, such as Eliezer Ben Bashe Leah. One does not mention his father’s name.
Mentioning the Rabbeim: It is customary amongst Chassidim to mention the name of the Rabbeim that they were Chassidim of in Yizkor. This has an effect on the Chassid saying it.
Mentioning men and women separately: Men and women are to be mentioned separately in Yizkor.
Charity: One is to pledge charity during Yizkor on behalf of the soul of the deceased.
Yizkor during the first year of Aveilus:
When Yizkor is taking place during the first year of Aveilus, the mourner remains in Shul for Yizkor, although he does not recite anything while there. He is not to recite the Yizkor even quietly.
After 12 months in a leap year: One who is still prior to the first Yartzite, but is past 12 months of mourning, is to remain in Shul and recite Yizkor regularly.
If the mourner needs to say Yizkor for another parent who is past the 1st year: If one is within the year of one parent and past the year for another parent, then only the parent’s name that is past the year is to be mentioned in Yizkor.
8. Mashiv Haruach uMorid Hageshem:
Mashiv Haruach Umorfid Hageshem is recited beginning from Musaf of Shemini Atzeres. On Shemini Atzeres prior to the silent Musaf the Chazan announces Mashiv Haruach Umorid Hageshem and it is then recited in the Musaf prayer and every prayer thereafter. See Chapter 7 Halacha 3 for the full details of this matter!
If one has still not Davened Shachris:
If a person who is not praying with a different minyan heard the announcement of Mashiv Haruch U’morid Hageshem before praying Shacharis, then he should say this phrase in Shacharis as well [as in Mussaf].
9. Shnayim Mikra:
10. Entering the Sukkah towards the conclusion of Shemini Atzeres: 
With the approach of sunset on the afternoon of Shemini Atzeres one enters the Sukkah (and eats or drinks something there) to bid it farewell. It is not the Chabad custom to recite the prayer that begins yehi ratzon upon taking leave of the Sukkah.
 Rama ibid
 Michaber ibid
 M”B ; Admur in Siddur writes Shemini Atzeres Hachag Hazeh
 Likkutei Torah “Bayom Hashemini” p. 172; Or Hatorah Shemini Atzeres p. 1818; Melukat Alef p. 234; Melukat Beis p. 289; Vetzaruch Iyun why in the footnotes of the Mamarim Melukat ibid the Rebbe does not not make mention of the source in Likkutei Torah
 Mamar Shabbos Teshuvah 5723
 Sefer Haminhagim p.
 Sefer Haminhagim p.
 Michaber 666:1
 Michaber 669:1
 The reason: As Shemini Atzeres is considered a separate festival than Sukkos 
 Michaber 668:1
 Michaber ibid; Sukkah 47b
Other opinions and custom: [M”A 668:2]
The reason: As in the Diaspora, the day was traditionally a Safek if it is the seventh day or the 8th day. [Michaber ibid]
 Michaber ibid; Sukkah ibid
 The reason: As doing so would contradict the day of Shemini Atzeres.
 Other opinions: See Piskeiy Teshuvos 668:1-2
 Implication of M”A 668:2 in name of Maharil “And after the morning meal one is to go home”; 1st approach in Machatzis Hashekel based on M”A 668:2 Derech Chayim ;
 2nd approach in Machatzis Hashekel 668:2
 M”B 668:
The Misheneh Berurah rules that it seems logical to say that a person has the right to eat wherever he chooses.
 Sefer Haminhagim
 See M”B 668
 M”A 668:2; Poskim brought in Shaareiy Teshuvah 668:3; Darcheiy Moshe,Levush, Shut Nodeh Beyehudah.
 The reason: [M”A ibid]
 Gra in Maaseh Rav 216; and other Achronikm
 The reason: due to doubt of whether it is the 7th day.
 The reason: As otherwise it appears that one is adding an extra day to the Mitzvah which transgresses Baal Tosif. [Michaber ibid] Nontheless, in truth one does not tranggress Baal Tosif unless he actively intends to fulfill; the Mitzvah also on the 8th day. [M”A 666:2; Taz 666:1]
Does this law only apply if one does not have room at home: This ruling of the Michaber ibid was written regarding one who does not ahjve anywhere to put the furniture in his Sukkah and is hence forced to eat there. Vetzaruch Iyun if one may simply chose to eat in the Suikkah, upon making a valid recognition, simply for purposes of leisure, even if he has room at home to remove the furniture, or he has a separate set of furniture at home.
 The law by a large Sukkah: Kaf Hachaim 666:5
 See Shaareiy Teshuvah 668:2
 Beis Yehuda, brought in Birkeiy Yosef 668 and Shaareiy Teshuvah ibid
 Birkeiy Yosef 668 brought in Shaareiy Teshuvah ibid
 Siddur Admur
 Sefer Haminhagim p.
 Michaber 668:1
 The reason: As Shemini Atzeres is considered a separate festival then Sukkos.
 Sefer Hasichos 5704 p. 32; 5697 p. 16; Hamingaim ?; Otzer Minhagie Chabad Tishreiy p. 368
 Sefer Haminhagim p. 147 [English] based on Mamarim Haketzarim of Admur Hazakein p. 454
 M”A 240:3 in name of Arizal “Ein Leshameish..; Or Tzaddikim 27:11; Birkeiy Yosef in name of Ramaz, brought in Shaareiy Teshuvah 668:4 that it is forbidden to do so; M”B 240:7
 Admur 494:3 regarding Sukkos; M”A 240:3; Chesed Lialafim 240:3; Siddur Yaavetz; Chayeh Adam 130:22; M”B 240:7; Kaf Hachaim 240:5
 Shlah p. 213 brought in Kaf Hachaim 581:86 reagrding the night of Rosh Hashanaha
 M”B 240:7; 581:26; Kaf Hachaim 240:5; See Seder Hayom brought in Kaf Hachaim 581:86; Machazik Bracha 581:4; Ben Ish Chai Netzavim 9; Chayeh Adam 139:7; Kaf Hachaim 581:88.
 Michaber 668:2
 Michaber ibid; Sefer Haminhagim
 Michaber 668:2; See also 669:1 regarding Simchas Torah reading for Diaspora communities
 The custom of Yizkor on Yom Tov is first mentioned in 621:14 regarding Yom Kippur; Regarding other Yomim Tovim: Nitei Gavriel Aveilus 2 78:4 that so is custom even though there is no known source for this in Poskim [See there footnote 11]; The following Poskim mention the custom of reciting Yizkor on Yom Tov: P”M 547 A”A 2; Kav Hayashar 86; Yalkut Hagershoni 621:2; Betzel Hachochmah 4:119
 Luach Kolel Chabad
Other customs: Many communities in Eretz Yisrael are accustomed to recite Yizkor immediately after the blessings of the Haftorah, prior to reciting Sisu Vesimcha.
 Gesher Hachaim 31:6
 Shaareiy Efraim 10:32
 The reason: This is due to Ayin Hara.
 Hamelech Bemisibo 1:321 [printed in Shulchan Menachem 2:250]; However in Luach Kolel Chabad it says to light it.
 Igros Kodesh 3:220 [printed in Shulchan Menachem 2:250]
 Kaf Hachaim 284:37 based on Zohar; Siddur Torah Or; Hamelech Bemisibo 2:166; Igros Kodesh Miluim, [printed in Shulchan Menachem 2:251]; Mishnas Sachir 2:233 that so is the custom in Ungarin; See Divrei Torah Munkatch 2:90; Nitei Gavriel 79:14 in name of Poskim
Other customs: Some are accustomed to mention the name of the father by Yizkor. [See Zohar brought in Hamelech Bemisibo ibid; Mishnas Sachir 2:233 that so is the custom in Poland; Nitei Gavriel 79:14 in name of Poskim and that so is the custom]
 Toras Menachem 46:343 [printed in Shulchan Menachem 2:252]
 Nitei Gavriel Aveilus 79:13
 Igros Kodesh 3:220 [printed in Shulchan Menachem 2:251]; Hamelech Bemisibo 1:309; Otzer Minhagei Chabad Yom Kippur p. 222
 This is learned from a play on words “Eitz Chaim Hi Lamachazikim Ba”, that one is to hold on to the Eitz Chaim for long life. [Hamelech Bemisibo ibid]
 See Admur 621:14
 Sefer Haminhagim p. 125 [English]
 So is the final ruling of the Rebbe in Sefer Haminhagim ibid, unlike Igros Kodesh 3:7 [printed Shulchan Menachem 5:308] in which the Rebbe directs to recite the Yizkor silently
 Directive of Rebbe Rashab to Rav Yaakov Landa brought in Otzer Minhagei Chabad Yom Kippur 195
 Admur 114:1; Michaber 114:1; 668:2
 Sefer Haminhagim
 After [midday] of Hoshana Raba. We however do not read Shnayim Mikra of Vezos Habracha on the night of Hoshana Raba [after the Tikkun] as is the custom of others. [Sefer Haminhagim p. 145 English, unlike the custom brought in Ketzos Hashulchan 72 footnote 4; So concludes also Peri Megadim A”A 285:10 that although many have the custom to read on the night of Hoshana Raba, it is best to read it on Erev Simchas Torah, and so concludes Ketzos Hashulchan ibid.]
Other customs: Many in Eretz Yisrael are accustomed to read Shnayim Mikra of Vezos Habracha on the night of Hoshana Raba after completing the reading of Mishneh Torah.
 As Vezos Habracha is read on Simchas Torah and has not yet been read during the year, hence it is similar to all weekly Torah portions which must be read Shnayim Mikra prior to their being read. [ibid]
 Sefer Haminhagim