When the red velvet curtain finally opened, Marc Jacobs' 56 models were arrayed tableau vivant-style in front of an enormous set of French doors—the kind you might see in a Paris salon. What you noticed first were the hats. Multicolored, with knit crowns, and short or wide brims, they made the gangly teenage girls onstage hold themselves like proper ladies. Yes, fashion's favorite change agent was at it again.

Last season's billowy layers were nowhere in sight. The collection began with a long coat, ribbed sweater, and trousers with loose stirrups that gave them a clean, sharp line. Moving on, Jacobs showed printed satin and matte jersey shirtdresses to the mid-calf, and belted alpaca tunics over slim cropped pants and knee-length skirts. There were jumpsuits straight out of the seventies. "I wanted something narrower," said the designer, describing the show's new silhouette. Duchesse satin minidresses were cut trim and A-line with a fringe of pleats at the hem, or they came draped, wrapped, and sashed from the shoulders.

This was American sportswear, but with a European sense of impeccability. Some might call it "grown-up." Jacobs, explaining that the collection is a reflection of what's going on with him personally, called it restraint. (Though the term can hardly be used to describe the show's stacks of plastic bangles and Bakelite-heavy handbags.) One look at the designer and you're reminded that he's been spending time at the gym—those were pecs beneath his crisp blue shirt. The experiments with volume that he's been focused on in the last several collections have now gone the way of his extra weight. It might take a season for designers who've followed his lead before to catch on. But less, when it looks this chic, really is more.