During the mourning period, the mourner recites Kaddish on behalf of the soul of the deceased. This recitation is very important for the deceased, as it can assist him in his judgment before the Heavenly Court and tip the scales in his favor.

The Mourner’s Kaddish is recited at the funeral, as well as at designated points during prayers in the synagogue throughout the mourning period and on the anniversary of the death (known in Yiddish as the yahrzeit). During the year of mourning it is customary for the mourners to say the Rabbis’ Kaddish at the end of public Torah study and at fixed points during prayers in the synagogue.

Further reading: For more on the significance of Kaddish for the soul of the departed, see A Concise Guide to Mahshava, p. 29. The full text of the Mourner’s Kaddish appears in the chapter that deals with the laws and customs of funerals and burial; see p. 504.

The Mourner’s Kaddish is recited by the sons of the deceased for eleven months. In the event that the deceased did not have sons, it is customarily recited by another descendant or relative, but if necessary, one can ask or even hire someone else to recite Kaddish for the deceased. Boys who have not reached the age of bar mitzva (thirteen) may nonetheless recite Kaddish for their parents.

If a person must recite Kaddish for another relative while his parents are alive, e.g., his wife or one of his children died, he should ask his parents for permission to say the Mourner’s Kaddish during their lifetimes.

In most communities, the custom is that women do not say Kaddish. In other communities women may recite Kaddish if they so desire (according to some opinions, only if the deceased had no sons), and in this regard there are different customs: Some maintain that she should recite Kaddish only if a man there is also saying Kaddish, while others permit Kaddish to be recited by a woman without any such conditions. In any case, a minyan of ten men is required for the recitation of Kaddish, including Kaddish said by a woman, and they must all respond with “Amen” in the appropriate places.

Although the period of mourning for a parent lasts twelve months, one recites Kaddish for only eleven months. The reason for this is that the Mishna states that “the punishment of the wicked in Gehenna is for twelve months” (Eduyyot 2:10). Consequently, if a son were to say Kaddish for his father or mother for twelve months, it might appear that he suspects them of having been wicked, which is disrespectful. Therefore, if the parent died, for example, on the fifth of Av, the period of saying Kaddish will end eleven months later, on the fourth of Tamuz. In a leap year, it will conclude on the fourth of Sivan.

The above practice is the most widespread, but there are other customs as well. Some stop saying Kaddish at the end of the eleventh month for a week and then resume it until the end of the twelfth month. Others do not stop at the end of eleven months, but say Kaddish continually until a week before the conclusion of twelve months. Each person should follow the custom of his family and community.

It follows that one who says Kaddish for someone other than his parents may do so throughout the twelve months following the death, since the reason for avoiding this ordinarily is the parent’s honor, which does not apply in this case. Nevertheless, as there are several opinions on this matter, it is recommended to consult a rabbi.