The Mourner's Kaddish can only be recited in the presence of a Minyan (quorum of ten Jewish males over age thirteen) during a prayer service, or after reciting Psalms or Mishnayot. It is normally recited at specific points during each of the three daily services. Kabbalah explains that a son who recites Kaddish for his father or mother saves them from certain judgment. One should, therefore, do the utmost to recite Kaddish at every opportunity during the first eleven months from the passing, and on each Yartzeit thereafter.
Women may undertake to do a specific mitzva in honor and memory of the loved one. Our sages state that for them, this brings the same merit to the soul as the recitation of Kaddish.
Leading the Prayer Services
Many mourners make a point to lead the weekday prayer services in their synagogue for the entire eleven months (less one day), for then one can recite the different forms of Kaddish throughout the services. This adds more and more holiness to the soul of the departed. By leading the services, one also joins the merit of all those praying and praising G‑d to the soul of their dear departed.
In the case when there are two mourners in one synagogue, there are several ways to proceed. If there are at least two Minyanim (twenty or more Jewish men over the age thirteen) present, separate services can held in different rooms or at different times, allowing each mourner the opportunity to lead the services and to recite Kaddish. Some authorities oppose the idea of making different minyanim because of the concept of "a large number of people gives greater glory to G‑d."
If there are not enough men to form two minyanim, then those saying Kaddish can take turns leading the services. During the morning service, they can each lead for different sections of the service. One should follow the custom of his community.
If One Cannot Lead the Services
If one cannot lead the services, one must still pray with the Minyan and recite the Mourner's Kaddish at the designated points. If one cannot attend all three daily services, he should at least attend one of them to recite the Mourner's Kaddish.
If the Deceased Did Not Leave Any Sons
If one did not leave any sons, or if it is impossible for the sons to recite the Mourner's Kaddish every day with a Minyan, one must hire someone to recite the Mourner's Kaddish in the merit of the deceased. It is preferable that this person should not be reciting Kaddish for anyone else at the time, but it is not imperative.
Hiring a "Kaddish proxy" is not an ideal first choice and the option should not be misused for convenience or to discharge oneself from duty, but only in a case of genuine need.
When a person is hired to recite the Kaddish, the mourner should still study Torah and give charity (except on Shabbat and Jewish holidays) on each day that Kaddish is recited.
Reciting Kaddish for Eleven Months
The Mourner's Kaddish is recited during all prayer services for eleven months, less one day when recited by a son, and eleven months and three weeks, when recited by all others.
Why is Kaddish recited by son(s) for only eleven months, less one day? According to Kabbalah, the soul of the departed is judged by a Heavenly Court. If one's good deeds are outweighed by one's sins, the soul undergoes a painful spiritual cleansing. Depending on the sins, the cleansing period could last up to twelve months, following which the soul is allowed into its eternal spiritual resting place. Reciting Kaddish eases this judgment and any travails the soul might have to endure.
However, one does not recite Kaddish the full twelve months out of respect for the departed. Pausing a month early indicates our confidence that the person's life was sufficiently meritorious to have avoided the full twelve months of cleansing. From another perspective, a son stops reciting the Mourner's Kaddish earlier than others because he still is obligated to honor his parents - even after their passing.
Directions for Reciting Kaddish
The Kaddish can only be recited in the presence of a Minyan (quorum of ten Jewish males over age thirteen) and only following the recitation of prayers, Psalms, or Torah study.
The Kaddish is recited aloud, while standing with the feet together.
The one saying Kaddish should pause after each paragraph to allow the congregation to respond, as indicated.
It is customary for the one saying Kaddish to bow the head while reciting certain words. These words are bracketed by the following symbol: ◦. When the symbol appears before a word, bow the head forward, and remain bowed until the word that ends with the same symbol, then raise the head.
Before the final paragraph of "Oseh Shalom..." one takes three steps back, and upon concluding the Kaddish, three steps forward. It is also customary to incline the head right, left, and straight ahead, while reciting certain words in this paragraph (see instructions below).
While reciting Kaddish, have in mind that you are performing the positive mitzva of sanctifying G‑d, based on the verse, "I [G‑d] shall be sanctified amidst the children of Israel" (Leviticus 22:32).
Mourners recite Kaddish up to six times during the morning services, and twice during the afternoon and evening service, for a total of ten times on each day, as follows:
During Shacharit (morning services):
1)Kaddish D'Rabbanan following the readings before Hodu.
2) Kaddish Yatom, following Shir Shel Yom.
3) Kaddish D'Rabbanan, following the readings before Olaynu.
4) Kaddish Yatom following Olaynu.
5) Kaddish Yatom , following the recitation of the daily Psalms.
6) Kaddish D'Rabbanan, following the studying of selected Mishnayot.
During Mincha (afternoon) and Maariv (evening) services:
1) Kaddish Yatom , following Olaynu.
2) Kaddish D'Rabbanan , following the studying of selected Mishnayot.