Need Help with Bat Mitzvah Etiquette

Dinner and dance; think wedding attire. Dress works. Gift, if I remember correctly, is given in increments of 18. I forget the reason. So if you want to give say $100you would give $108. Hope this helps.

My kids have gone to several of these. It's just like going to a wedding or other fancy event at church, the only difference is that Jewish Temples ask that girls/women keep their shoulders covered during services, so if you are going to wear a sleeveless dress or something with thin straps bring a light wrap or sweater for the ceremony itself.
Cash was always what we gave, usually $25 or so for the child and another $25 for whatever charity they are supporting (there was always a note re this in the invitation.)

To the service, what you would wear to church. The dinner is usually a bit dressier but it depends on the venue.

As for a gift, money is always great. Increments of 18 are good luck (because the word for "life" is chai, and the Hebrew spelling of that then adds up to 18).

I have friends planning one now. It really is like a wedding in some cases. The venue should give you an idea of the expense they're going to and then gift depends too on whether its your whole family or not. So I would treat it the same as if you were going to a fancy or casual wedding as dictated by the venue and general sense from the invitation.

Don't worry about the spelling - it's an approximation of the Hebrew so, while you used the most common spelling, there are others. (Think Hanukkah/Chanukah.) A joint service for 2 girls is a b'not mitzvah (Beh-NOTE MITZ-vah) although to be completely correct, the teens themselves ARE each a bat mitzvah ("Daughter of the commandment").

The ceremony is part of a regular service, so dress as you would for church. If the invitation says "dinner and dance" and if it's a morning service (usually it is), then there's a break and you could, conceivably, change clothes. If it's lunch and a party right after the morning service, then I wouldn't get too fancy. It's likely a DJ. That's what my son had and it was not formal at all. I wouldn't do fancy wedding attire for that. If, for some reason, there is an afternoon ceremony followed by dinner and dance, then it's very unusual.

Lots of times, women wear a dress with a wrap or jacket to the synagogue, then remove them for the party. It also depends on whether the festivities are in the synagogue itself or in a country club/restaurant, and whether the synagogue itself is affiliated with the Reform movement or the Conservative. You can message me with particulars if you like.

Many bar/bat mitzvah services that have a large number of non-Jewish guests will include some commentary by the rabbi or a hand-out from the family to explain key concepts. You can participate in anything you wish, or simply watch/enjoy. You should stand when the congregation stands but you don't have to do anything else that isn't comfortable for you.

You don't bring anything to the service. If you bring a gift to the party, it can be a hardship for the family (they have to collect everything and take it home) as well as occasionally a security issue (think of all the wedding gifts that are lifted by "crashers" or unethical staff).

Gifts can be cash (in multiples of 18 is common, because the Hebrew numbers for 18 are the same as the Hebrew letter for "chai" or "life" - think "L'chaim - to life"). So a check for $18, $36, or $54 is common. I would give separate checks to each kid. Some people give Jewish jewelry - Star of David earrings or necklace, for example. You can also give something non-religious - other jewelry, for example, whatever you think the kids would enjoy. You can find bat mitzvah cards in any big card store. I suggest something celebratory but not too far to either extreme (not super-religious, but not filled with bad joke, stereotypical puns either).

Let me know if you need additional help.

When my girls have attended, they (me) give $50.

You did spell it right--I suppose it might even be written a little different because it's twin girls, but that's irrelevant.

The other answers have you covered on the attire--I personally would suggest that you wear shoes and clothes you can dance in. It's traditional to dance the hora at some point in the reception, which is a line dance that involves everybody, and you don't want to miss out on it. One of my friends once told me that at a Jewish wedding, dancing means that you approve of the match, and I feel like it's similar for a bat mitzvah, namely that the guests dancing says that they fully support the young people and their family in this special moment. For the gift, gift cards or cash in multiples of 18 are indeed traditional, and there probably will be a charity cause (maybe two different ones, since each girl will have had her mitzvah-good deep--project) to which you can contribute in the gals' honor. I also think it would be fine to ask the gals' parents whether another gift, such as matching chai or Star of David pendants would be appropriate.

Enjoy!

I would ask the parent of the honorees.