What's the Dress Code for “Semi-Formal”?

We all know that your prom is a "formal" occasion.  Girls are supposed to wear gowns (or some other suitable fancy dress), and guys are supposed to wear tuxedos.  But what do you where to something that's designated as "semi-formal"?

Many high schools have semi-formal dances in the beginning of the school year, so it's not too early to start thinking about this now!

The basic rule of thumb is that semi-formal falls somewhere between "casual" and "formal."  That means that guys can't go in khaki pants and polo shirts, but they don't have to wear tuxedos, either.  A suit with a nice button-down shirt is appropriate for something semi-formal.

But what about girls?

• Fashions change, but some basic rules stay the same.  Generally, a semi-formal dress can range from a cocktail dress to something along the lines of a tea-length dress.  So you want the hemline somewhere between 1" above the knee and 3" above the ankle.
• Any silky fabric is appropriate.  For something semi-formal, it might be a little overboard to wear something overly-poofy or princess-like.  (Save that for prom!)
• There's also some freedom as far as shoes are concerned.  Dress heels are appropriate, but you could also get away with something flat.  Just stay away from flip flops!