The signal piece in the Row's new Resort collection is a fisherman's rain slicker cut from canary yellow leather so soft it almost defies belief. Ashley and Mary-Kate Olsen said they were looking at uniforms—of sailors, of Japanese workers, of school children—for ideas this season. The concept provided some great basics upon which to riff: extravagant fisherman knits (not just a sweater, but also a skirt), a worker's jacket cut from indigo and belted over a long cotton voile skirt, a double-breasted prep school suit with pleated pants cropped well above the ankle. In the Olsens' hands, nothing remains a basic for long. They developed most of the lineup's exquisite fabrics themselves and have a savvy eye for other materials. You won't touch anything more delightful all season than the long-haired alpaca of their rose-colored vest and matching oversize clutch. A crisp blueberry raincoat trimmed in mahogany (their color names, not ours) was quietly luxurious in another way: You can unzip its lining and wear it as a coat on its own.

Denim is another sort of uniform. It, too, got the Olsen treatment, turning up in the palest of blues on a pair of full-leg jeans and in a deep indigo that wasn't really denim at all, but a deluxe stretch cashmere that looked like it, in the same trouser shape. Their other idea, they said, was to use high-end fabrics in a casual way. That's a combo that's hard to resist.