Simone Rocha is one hell of a fast learner. Her show today not only affirmed the buzz that's been building around her brand since it launched two years ago, on London's Fashion East stage, it also improved on her terrific solo debut last season, both by elaborating its themes and trimming its excesses.

Rocha is an incrementalist. She works by carrying her good ideas forward and working them over. With this collection, you perceived her arriving at a summation of the one big idea that's been driving the look of her collections from the start. It's an idea about youth, and a certain kind of rebel schoolgirl slouchiness—one that Rocha is precise in rendering. Last season, she perfectly captured the rude glamour of a snub-nosed teenager slunking around in her oversize, hand-me-down coat. This season, that schoolgirl took on a somewhat more polished air, in little dresses and suits that would come off atavistically ladylike if they weren't sheer in weird places, or unexpectedly proportioned, or made of, say, plastic.

Rocha's techno sensibilities regarding fabrication seem like the design signature that she'll carry forward, once her schoolgirl phase has passed. Her materials are, in every sense of the word, fantastic; highlights this time out included plastic laces of neon daisies or scribbly black dots. But Rocha isn't so enamored of space-age materials that she turns up her nose at organic ones, and her use of crochet and cotton broderie anglaise gave this collection some of its warmth. Most of that, though, came from Rocha's sensitivity to her girl and the story she was telling about her. There was something moving, frankly, about the model walking down the runway in a gold-toned dress of desiccated tweed; she had the vibe of a young woman off to her first fancy date, wearing unfamiliar grown-up clothes in a sweetly unfamiliar way. And thanks to Rocha's halolike headbands and her trademark Perspex-soled heels, that girl was pretty much walking on air. Ah, youth.