What should I wear to a Greek Orthodox wedding ceremony?

For the ceremony you should be tastefully dressed (i.e. covered shoulders, no short skirts, tasteful neckline. Typically a black tie event is calling for an evening gown, not a little black dress. So you're going to want to wear more of a floor length dress. I have seen a lot of women dressed in black at Greek Orthodox weddings, but I wouldn't make it a point to wear a black dress if I didn't already have one.