Your invitation will give you an indication of what is appropriate to wear. It should state the formality of the dress expected.
There are different levels of formality…
If the event is “Black Tie” or “Formal”, it is appropriate to wear a dinner suit, formal shirt and bow tie, with a waistcoat or cummerbund. For a more contemporary formal look, you could wear the Picasso or Boston with a formal shirt, bow tie or straight black tie. You can top this off with a waistcoat. A business suit is not suitable for a Black Tie event.
White Tie is very formal. If an invitation states “White Tie”, the standard of dress required is Evening Tails, Marcella shirt, Marcella waistcoat, white bow tie and black cummerbund. White gloves are also expected. This is a very strict code of dress. A dinner suit is not suitable for a White Tie event.
School balls are formal events. A School Ball invitation will state the required dress code. Formal but fun is the way to go.