What do I wear to a Bar Mitzvah?
Attire
Guests at a bar/bat mitzvah celebration generally wear dressy clothes — for men, either a suit or slacks, tie, and jacket, and for women, a dress or formal pantsuit.
Kippah
A kippah (KEEP-ah) or head covering (called a yarmulke in Yiddish), is traditionally worn by males during the service and also by women in more liberal synagogues. Wearing a kippah is not a symbol of religious identification like the tallit, but is rather an act of respect to G-d and the sacredness of the worship space. Just as men and women may be asked to remove their hats in the church, or remove their shoes before entering a mosque, wearing a head covering is a non-denominational act of showing respect. In some synagogues, women may wear lace head covering. Most synagogues have a basket of kippahs (also called kippot) at the entry to the sanctuary, and bar/bat mitzvah hosts often provide custom-made ones that you can keep as a memento.
Prayer Shawl
The tallit (tall-EET or TALL-is), or prayer shawl, is traditionally worn by Jewish males and, in liberal congregations, by Jewish women as well. Because the braided fringes at the four corners of the tallit remind its wearer to observe the commandments of Judaism, wearing a tallit is reserved for Jews. Although an usher may offer you a tallit at the door, you may decline it if you are not Jewish or are simply uncomfortable wearing such a garment.