For Fall, Zac Posen was determined to bring more separates into his reliable mix of ZAC Zac Posen frocks. "It adds a 9-to-5 balance," said the designer in his Tribeca studio space, his team stitching away at the main collection in the sewing room next door. ZAC Zac Posen is his "secondary" offering, the one affordable enough for his evening-gown customer to buy multiple pieces of—a $1,000 day dress here, a $375 silk blouse there—and transform herself into a day-to-night Zac Posen woman.

The question is: Does she want that? Even when he's making tops and bottoms, Posen likes his girl dressed up, which can look a little old-fashioned for day. Leather skirts and jackets, printed with a dark red plaid better suited to wool, just didn't sit right. And to-the-rib-cage trousers, fashioned with multiple pleats at the hip to give them the silhouette of a long skirt, seemed impractical. The freshest looks were the long-and-short dresses and pussy-bow blouses in a pressed-flower print the color of a nectarine. They were polished but not too serious. The burnout knits, on the other hand, were too "granny's attic" to really last in a working woman's wardrobe. She'd much prefer one of his sharp blazers in herringbone stretch jacquard.

Lucky for her, Posen included a lot of distinctively seamed dresses and jackets. Those pieces were good enough to make more than a few of his special-occasion customers everyday ones, too.