For his main Fall collection, Thakoon Panichgul was inspired by neon, but there was darkness lurking under that light: It was the glow of Amsterdam's red-light district, as reimagined by the artists Ed and Nancy Kienholz for their piece The Hoerengracht, that provided the juice. There were peacock-feather prints and appliqués—for pride and vanity, cardinal sins both—and a basket weave detail lifted from confessional screens. That girl's all grown up, and naughty, too. But at Addition, Panichgul's kid-sister line, things are still sweet and nice. "It's a little groovier this season," the designer said in his showroom, and patterned poncho tops, culottes, and wide-legged jumpsuits backed him up.

There were echoes of the main line in some of the shapes, like the high-waisted, wide pants, but overall the muse was Addition's usual gamine. For Fall, she'll wear "teddy bear" faux furs (the best of them in a bomber, trimmed with military-trench details); ultra-fitted blazers with asymmetrical, slightly flaring backs; and loose silk dresses, whose prints mimic knit stitches. There was more leather than ever before, in response to buyers' demands: a single-breasted blazer in cadet blue on one hand, and tiny, quilted short shorts on the other—the sort you might get if you had your old 2.55 retooled into hot pants. The collection continues to expand, and so does the brand: Panichgul revealed that he'll soon be in need of more space than his current digs afford, thanks largely to the sales of Addition. And the showroom buzzed with buyers. Addition's not grown up yet, but it certainly is growing.