What should I wear to my sister's Hasidic Jewish wedding?

Mazal tov! Gottago answered the basics. Don't be surprised if many of the Breslovers in Israel look hippiesh. You may be used to wedding clothes overseas where people wear expensive outfits and tuxedoes. Many of the individuals that you meet in your sister's world will dress in a more relaxed fashion. (Think "Woodstock" meets the 21st century.)

It's your sister's special event, so it's nice that you're doing your part to make her happy! Your suggestion of a long dress is great, and you should maintain the modest clothing the entire time regardless of where you are in the hall. (There will probably be a photographer and a video camera making the rounds.) Wear appropriate footwear and comfortable clothing that will enable you to dance with the bride and her friends. The dancing will be the focus of the evening. Have a great time.

i would say tak to your sister, but jewish laws are cover the collarbone, elbow and knees. the breslov do not show any leg though, they wear tights and closed toe shoes, also nothing too form fitting. but, on that note, im sure everyone coming to the wedding is aware tthat our sister grew up non religious, no one will look at you weord if you are not dressed like everyone elses, bc believe me, even if you do dress with the above guidelines, every single breslov will know you are not breslov. good luck and mazal tov

Jewish law requires women to cover their chests up to the collar bone and arms to below the elbow. It would probably be most respectful if you wear a cardigan or stole that covers those areas. As for the reception, it doesn't really make a difference whether the men and women are separate, the rules still apply. At most orthodox weddings there are people who are not dressed according to Jewish Law, (usually non observant family and friends) no one is going to make them feel uncomfortable.

If you are uncomfortable, why don't you run it by your sis. She knows you and your background and she will tell you if it's important to her that you dress appropriately.

Gottago has given you the best answer, by far.

Collarbones can't show. Knees can't show. I'm not sure how much arm.

the photo of the two palestinian women, I would say is insulting.

and the others...well, just not terribly helpful.

My dad went to a Jewish family, the Women dressed very conservative. No twins showing alright?

I would rather tend to favor something like that outfit Red Sonja wears.

It never hurts to try something new.

No Cleavage here sweetie.

Cover all of your flesh.

Something like these clothes they're Jewish