Some women were in beaded gowns and many men were in tuxedo's. There is a wide range of what people wear on formal night. About the most casual I saw were men in dress shirt and pants and women in semi casual dresses. There are gowns and tuxedo's for rent on board if you don't have any, but really, just be comfortable. Just a tip...even on the informal nights in the diningroom, you can't wear shorts or sandles, but many men wore khaki pants and a sport shirt, while the women wore sundresses or dress pants. Our family really enjoyed dressing up each evening, though we never do at home!!