Cut from crisp Italian cotton in a slim blue-and-white stripe, this is the dress is the sartorial embodiment of a weekend in Amagansett: You'll throw on for your morning run to Amber Waves and end up wearing it straight on through dinner at Il Buca al Mare. It has a ruched U-neckline—perfect for showcasing a delicate gold pendant or two—and gently rounded sleeves with wide cuffs and mother-of-pearl buttons. The fit is relaxed and flowy, and there are side-seam pockets and a self-tie belt to cinch the waist—though we left the belt loops off, so you can wear it loose, too.