When Throwing A Formal Dinner Party, What Should The Attire Be For Myself And The Guests?

A formal dinner party has a double formality requirement. First, it is being held in the evening, which generally requires a formal atmosphere and second, you, who are throwing the party, have declared it formal. While truly formal attire usually consists of couture ball gowns and designer tuxedoes, unless you have guests who have these types of clothes available, they will most likely come dressed in dressy clothing that they would wear to a wedding – dresses and suits with ties. If you'd like your guests to wear truly formal wear, be specific on the invitation by stating 'black tie only' which will signify that they should find something more appropriate than an off-the-rack ensemble. Expect that some people, unless you move in wealthy society-type circles, will still not come dressed as you have specified.  If you'd like everyone to have a relatively similar look, consider providing bow ties or jackets for the men.