JUNE 2008: "More Carrie, Less Ugly Betty". Alexis Mabille, the French designer of fanciful bow ties, likes to think the bow trend began with him. "When we started three years ago, no one was doing them," he said. "Then we sold to Colette, and all the cool girls started to buy them."

"Now," he sniffed, "everybody is doing bow ties."

And, well, despite the fact that the formal adornment has been around for a while (Wikipedia, if you will, claims that it originated with 17th-century Croatian mercenaries), Mr. Mabille has a point. From the tightly tied traditional sort to the more flouncy and feminine, bow ties are big for summer and fall. And, yes, all the cool girls are wearing them.

The evidence: Sarah Jessica Parker, far left, fashioned a Margiela silk tie into a bow for a recent party for Christian Lacroix. At Cannes a couple weeks ago, Gwyneth Paltrow took a turn on the red carpet in a Chanel gown covered in them. And earlier in the season, Lauren Santo Domingo, left, showed off a bow tie look from Bill Blass fall collection. Peter Som, the house's designer, explained that it was inspired by a 1970s photo of Mr. Blass with a woman in a three-piece suit and bow-tie blouse. "She looked so strong and sexy at the same time," Mr. Som said.

Lately the stylist Lisa Marie Fernandez has taken to tying her paper-thin pashmina into a floppy bow. "You pull your hair back, put on a pair of diamond earrings and it's so chic," she said, adding that for an even more polished look, "a silk scarf from Turnbull & Asser" works well. Want a less expensive operation? Do like the Bill Blass team and buy some silk ribbon from Mokuba in the garment district.

Alexis Mabille silk mousseline bow tie, $350 at Henri Bendel.