While it's not necessary to wear a tuxedo to a semi-formal dance, it's not acceptable to wear jeans and a T-shirt either. If you're going to a semi-formal dance soon, know which clothes are appropriate to wear so you don't feel overdressed or underdressed on the big night.
Teenage boys don't have to worry about the hassle of finding the right tuxedo for this occasion. For a semi-formal dance, it's perfectly acceptable to wear a plain dress shirt with a tie. Check for stains and wrinkles on your shirt before you wear it out. Even the nicest dress shirts won't look presentable if they're dirty and wrinkled. Keep your tie simple; one with too many designs is distracting.
A dark pair of trousers or slacks will go along nicely with a dress shirt and tie. While black pants are the most practical, a pair of gray ones will also look presentable. Jeans and khaki pants aren't appropriate, even if they are your nicest pair. Always wear a belt with your pants.
It's always important to wear dress shoes to a dance, even if it's semi-formal. Sneakers or sandals are never acceptable. Wear a dark pair of loafers or dress shoes. Always wear dark socks with your dress shoes. Have your shoes shined before the semi-formal dance so they look presentable.
Grooming for a semi-formal dance is just as important as it is for a formal dance. Keep yourself neatly shaven and put gel or pomade in your hair to hold it in place. Put on deodorant and a few spritzes of cologne on your neck, wrists and chest. Brush your teeth and use a breath mint before your leave. Do not forget about your fingernails; nicely trimmed fingernails will give a positive impression.