It is not customary for women to recite Tachanun. Some explain that the reason for this is similar to the reason that women do not recite Maariv. Since they were both originally optional prayers, women did not accept them upon themselves (Tefillas Bas Yisrael 2,12).
Others explain that Tachanun creates a situation where we pray in every possible position. Pesukei D’zimra and Shema are recited mostly while seated, Shemoneh Esrei while standing, and Tachanun in a bowed position. Since many halachic authorities rule that women are not obligated to say Pesukei D’zimra and Shema, they do not recite Tachanun either (Machzeh Eliyahu 20).
We may add that throwing oneself to the floor may be immodest for a woman. Since Tachanun originally involved falling before Hashem, women did not say this prayer. Even today, when the custom is to recite Tachanun while leaning on one’s arm, women still do not say this prayer.
Text Copyright © 2010 by Rabbi Daniel Travis and Torah.org