Old etiquette: Don’t wear white or black or red.
New etiquette: Black and red are perfectly fine, but white is still the ultimate wedding no-no.
What to wear: Let the invitation, the season, and the hour be your guides. (If you’re at a loss and you’re close to the bride, ask her what’s right; otherwise, consult the maid of honor or the bride’s mother.)
"For day weddings, which tend to be more casual, steer clear of anything heavily beaded or sequined," says Lauren A. Rothman, founder of Style Auteur, a fashion-consulting firm based in Washington, D.C. Instead, opt for a knee-length dress in a material like cotton; in warmer weather or regions, strapless styles and open-toed shoes get the nod of approval. "Simple hats" also earn a thumbs-up, says Amy Lindquist, head of Lindquist Fashion & Image Consulting, in Minneapolis. If the ceremony is in the afternoon and the reception in the evening and the invitation doesn’t specify dress, assume the event is semiformal, which calls for a cocktail dress or an evening suit in a color that won’t upstage the bride. “Pale pink is OK―hot pink is not,” says Lindquist.
Black tie once meant floor-length gowns. Now, at all but the grandest affairs, dresses as short as knee-length are acceptable, provided they have a semiformal or formal cut and fabric; silk or a silk blend, for instance, would be appropriate. As for wearing a strapless or sleeveless dress in a house of worship, some have strict rules about covering up; check the protocol beforehand or bring a wrap.
Should you be invited to the rehearsal dinner, “they vary greatly in formality, so note where it’s being held,” says Lizzie Post, an etiquette authority, an author, and a spokesperson for the Emily Post Institute. In general, “cocktail-party rules apply,” Joseph Williamson, a fashion stylist in New York City. “Save your better outfit for the big day, but wear something dressy to the dinner. A dress and a jacket or a cardigan with some sparkle would be nice. But keep it understated.” Remember―there’s only one shining star at matrimonial shindigs, and it’s not you.