The Full Spectrum

From most formal to least, here is what each code actually asks for:

• White tie: the peak. Floor-length gowns and tailcoats, reserved for state dinners and a handful of grand events.
• Black tie: tuxedos and formal gowns. Galas, award nights, formal weddings.
• Black tie optional: a tux if you have one, otherwise a dark suit; a gown or dressy cocktail dress.
• Cocktail: polished but not floor-length. Dark suit, knee-length or midi dress.
• Semi-formal: a step down from cocktail, still pulled together, never casual.

Unsure which applies? Ask the host. Clarifying a code is never embarrassing; arriving in the wrong outfit is.