Have you been invited to a wedding, but aren't quite sure what to wear? Deciphering the type of occasion from the invitation - formal, semi-formal, informal - can be tough. The "rules" vary for formality and also for different times of day. In general, women typically want to wear a dress. It doesn't need to be full-length, unless it's a very formal wedding - and just about any color goes, except for white - although some colors are more fitting for different times of the year.