A sundress is appropriate for a casual summer wedding provided the weather is hot, the dress is in good taste (not too low, too short or too tight) and it looks good on you. Also a sundress is perfect for beach weddings in the summer. As far as the color, pastels, bright, summery colors and floral prints are popular for sundresses. It is good to have a coordinating color wrap for when the sun goes down. If you are attending a beach wedding you will want to have comfortable shoes to walk in on the beach: flip-flops, sandals or flats. Bring sun screen, sun glasses and a floppy hat to protect from the sun. Simple style earrings or light weight drop earrings are more comfortable than heavy earrings if the wind whips up.