The wedding is a semi-formal event. Semi-Formal is dresserier than casual, but not as formal as black tie.
WOMEN: Polished, elegant outfits like cocktail dresses, sun dress, or a dressy jumpsuit. Shoes should be dressy flats, heels, or wedges.
MEN: Suit and tie, blazer with dress pants, or dress shirt and dress pants. Shoes should be dress shoes, (ie: oxfords, derbies, loafers.)