Formal wear (more often in the United States) or formal dress (in the United Kingdom) is a general term used to describe men's clothing suitable for formal events, including weddings, debutante balls, etc. Traditional 'rules' govern men's formal dress; these are strictly observed at socially conservative events such as royal weddings, and serve merely as starting points for the creative formal wear seen at high school proms and entertainment industry awards shows.

For degrees of formal wear, see evening dress or white tie, black tie, and morning dress.

Formal clothing for women is generally categorized as evening wear.