Backstage, Jason Wu said he wants to keep challenging himself technically. The way he set out to do that for Spring was to take casual, everyday pieces of American sportswear and re-create them in beautiful, super-luxe fabrics. The process seemed to produce a newfound playfulness in the designer—some of the clothes were almost quirky. Early on, for example, there was a sweat suit complete with a hood in navy tweed, and a roomy forties-ish romper in denim silk. Later he paired a tulip skirt with a black tee striped in multicolor Swarovski crystals. Hair and makeup that evoked Daphne Guinness added another touch of eccentricity.

When it came to the evening portion of the show, though, Wu was mostly back in earnest mode. He loves a one-shoulder dress, and you can hardly fault him: Michelle Obama, of course, wore a one-shoulder gown of his design to the Inaugural Balls last year. The examples in his show today were knee-length, but they came in all sorts of fabrics, from high-drama gold faille with a 3-D sculpted sash to a younger, cheekier aqua-and-black point d'esprit. As he did for Resort, Wu really let it rip when it came to colors, mixing the blushing pink feathers of a strapless number with an electric-lime-green ribbon belt, and violet with candy-apple red on a bustier dress. The only thing challenging about these party dresses will be keeping front-row starlets like Kerry Washington from clamoring to wear them. This show was a confident leap forward for the 26-year-old designer.