After Marc Jacobs' high-powered presentation, it's official: Spring is all about color. Designers are staging a backlash against fall's somber mood, and Jacobs is spearheading it.

Using a long pier off Manhattan's Meatpacking District as his runway, Jacobs presented what is sure to become one of the season's most influential collections. Lilac shirts, marigold pants, dandelion sweaters, and sweet tulip-print dresses brought to mind a Berkeley student listening to Donovan or the Strawberry Alarm Clock in the late sixties—if flower children had ever displayed such a witty way with proportions and chromatic combinations. Mack-daddy suits with wide lapels, plenty of topstitching, and generous bell-bottoms were worn with pale plum shirts; a folksy collage jacket was trimmed with vivid printed bands and paired with a blueberry suede skirt. Rainbow jersey dresses, floral-print halters, and petal-embroidered shirts were simultaneously sweet and mischievous.

When the show ended to thunderous applause, a faux backstage wall magically parted, allowing guests like Sarah Jessica Parker, Gretchen Mol, Hilary Swank, Lisa Marie, Donald Trump, and Monica Lewinsky to venture into the backroom. Jacobs had created an elaborate party space overlooking the Hudson River, complete with grass-covered floors, picnic tables overflowing with fresh fruit, and even a fire boat that sprayed jets of water in the distance.