Should guests dress casual or formal?

At most Bar/Bat Mitzvahs, all guests are encouraged to dress semi-formally and conservatively (at least for the ceremony portion). It is an honor to be asked to attend someoneā€™s Bar Mitzvah ceremony and guests should all respect the rules and restrictions of the synagogue. Typically girls wear dresses or skirts that are knee length with covered shoulders (maybe with a sweater or shawl) and a conservative neckline. Boys are encouraged to wear long sleeved shirts with ties and if they are Jewish it is custom that they wear a kippah (skull cap). Girls may also be encouraged to wear a tallit (prayer shawl) which is handed to them when they enter the synagogue.