The image that best typifies the look—fresh-faced, carefree, and Birkenstock-shod—is that of a young Kate Moss shot by photographer Corinne Day back in the 1990s. Moss is the picture of alluring youth in a crop top, cropped jeans, and double-strap sandals. “That photo is one of my favorite pictures; my screen saver” says Fashion Assistant Emma Morrison. Having sported them as part of her camp counselor uniform in college, Morrison still has a soft spot for the classic tree-hugger shape, known as the Arizona, even though she also wears Giambattista Valli’s metal-studded take on the shoe.

Yet there are those who argue that the newer, streamlined versions are the chic way forward. “I remember when I wanted to wear my suede Arizonas on a family trip to New York, and my mother turned to me and said, ‘Are you crazy? You can’t wear Birkenstocks in New York! You look vulnerable!’ ” says Vogue.com contributor Jane Herman Bishop. “So I don’t wear that style anymore. They remind me too much of my high school self.” She favors a more elegant T-bar shape known as the Larisa, that has all the foot-slimming properties of the T-strap—the longtime favorite of comfort-seeking fashion girls, including the Olsen twins—but with the coverage of a traditional two-strap. Morrison and Bernard, on the other hand, have been scouring eBay for discontinued styles that come even closer to the Céline version. Their reasoning? A bulky shoe is actually more flattering on the leg than you would think.

Whatever the shape, the rules for wearing them in a stylish way right now apply across the board. “It can’t look like you’ve had them for years like in the old days; otherwise it reads hippie,” says Bishop. “A fresh pedicure is a must.” She suggests metallic leather or polished patent styles over the traditional beige suede for a more elevated feel. And it helps to counterpoint the look with a tailored pant, or ladylike dress. As Morrison puts it, “There’s nothing better than a really pretty dress with an ugly shoe.”

See 10 takes on the ugly-pretty sandal—summer’s must have shoe.

See more fall fashion here.