At first glance, an Ann Demeulemeester show looks like the homeward march of a tribe of Belgian Goths after yet another lost weekend in an Antwerp club. But in fact, Demeulemeester's business success is thanks to a following, not of club kids, but of women in their thirties and forties.

Strange but true: All those pieces—malleable, crunchy paper-light leathers, coolster blazers, asymmetrically traily knits, slouchy pants, and great boots—meld quite happily into the wardrobes of women who've been too busy working and raising children to have been near a basement dive for years. They'll sift through this collection as they always do, finding in it a way to wear color (shades of orange, this time) or adapt a frill to their lifestyle (on a dippy layered skirt, perhaps). The fashion crowd may lose patience with Demeulemeester's measured, skeptical approach to trend—not to mention those persistent dangling straps— but her customers would no doubt be horrified by too much change.

It's amazing to realize that Demeulemeester has been designing for almost 20 years; she emerged in Antwerp at the same time as Dries Van Noten, who celebrated his 50th collection with a massive party in Paris this week. Demeulemeester commemorated a personal turning point of her own, in a very different way, for spring: Some of her favorite signature T-shirts were printed with a black-and-white photograph of her son Viktor, who is now 18. "He left home this week to go to art school in Brussels," said the proud mom backstage. Sweet.