Wedding Attire, In Brief

Depending on the time of day, size, location, and overall "vibe" of your wedding, appropriate attire for you - and your guests - will change. Sure, if you're dead-set on a 25 person black-tie wedding in a rustic barn, then by all means, go for it. However, if you're looking for a little more concrete guidance on what's "appropriate", read on.

Colin Cowie Weddings

Black Tie

Wedding Size: 75+ guests
Time of Day: Evening
What It Means:

Men should be in tuxedos. Women have a bit more flexibility. It's no longer required that black-tie mean floor-length gowns. Shorter dresses are fine, but they should "special" and formal.
As a bride, you'll be looking at a floor-length gown. It doesn't have to be a ball-gown, but if you're inclined towards sparkles, sequins, embroidery, glitz, etc., this is the time to go all-in. You can also wear more jewelry.

Style Me Pretty

Cocktail

Wedding Size: Any
Time of Day: Evening
What It Means:

Men should be in jackets and ties, most likely suits. Women in, predictably, cocktail dresses. However, the wedding party can be in tuxedos and floor length dresses, if you so choose.
As a bride, you have your choice of gown length. Most brides choose floor length, but again, a special, more formal, cocktail length dress is perfectly fine, if that's you thing. You may want to glam it up a bit with fancy jewelry and makeup, however. You are the bride, after all... It's appropriate for you (and your wedding party) to look more dressed up than your guests.

Pinterest

Daytime

Wedding Size: Any
Time of Day: Morning or Early Afternoon
What It Means:

Groomsmen will most likely be in jackets w/ ties or suits. There is such a thing as a "morning suit" - see pics from Prince William and Kate Middleton's wedding for an example (a lot of the male guests, if not in the military, were in morning suits). They're a little outdated, frankly, and very uncommon in the U.S. Bridesmaids should be in tea-length or shorter semi-formal dresses.
As a bride, you can still go floor-length with your dress, but you might want to keep it simple if so. Daytime weddings usually mean it's time to go easy on the embellishments, especially rhinestones and other glittery elements. Lace, however, is perfectly appropriate! A shorter, tea-length or cocktail length dress or even suit is fine too.
Male guests will also likely be in jackets & ties (although, some may forgo the tie), and ladies will be in shorter dresses or suits.

Refinery 29

Informal

Anything goes! If you're getting married on a beach with a few friends as witnesses, or at city hall on a Friday afternoon, your attire is entirely up to you. (Although, I would suggest a breezy white dress or a smart, ivory silk sheath, for the respective venues mentioned prior!)