There are three views in a Bas Mitzva, Rav Moshe Stern, Beer Moshe, Debretziner Rav who holds that it is something being done by the reformers and if invited, not to go. There is no open distinction before reaching of age and after, whereas a bar mitzva puts on tefilin. Reb Moshe who holds that it is optional no mitzva involved like any other birthday party and Rav Yaakov Weinberg the Saridei Aish who says that it is necessary to make it so the girls should not feel left out. Examining all the pros and cons, I decided, for modesty reasons, to make it for women only.