When discussing the history of women’s hats in the United States, the designer and author Steven Stolman was reminded of Stephen Sondheim’s “Company,” in which Joanne wryly asks, “Does anyone still wear a hat?”

Hats come and go in women’s fashion, but there is one place you can always find them. Mr. Stolman is well aware of that. He was in Kentucky to help Britainy Beshear, the first lady of the state, get ready for the 151st running of the Kentucky Derby, which she was attending in a dress he designed and a hat he helped select.

No American sporting event can match the sartorial splendor of the Derby, and Mr. Stolman, who is no stranger to such affairs, having donned a top hat to attend Britain’s Royal Ascot races, had many opinions on what made a good hat (and many more on fascinators and elaborate headdresses being entirely separate things).

“I think that the whole goal should be that you see a beautiful lady wearing a hat,” he said, “rather than a beautiful hat being worn by a lady.”

In Mrs. Beshear’s case, that meant having Mr. Stolman pair a pink-and-white silk check shirt and skirt from his Steven Stolman for J. McLaughlin collection with a hand-blocked white sinamay hat by Gigi Burris that was trimmed with twisted goose feathers.

When looking ahead to the array of hats that would be seen in the crowd on Saturday at Churchill Downs, Mr. Stolman expressed some dismay that more than a few women were likely to choose poorly as they no longer had the help of trained milliners and sales people when shopping.

“Buying a hat online is really risky business because there’s no opportunity to see if it even fits,” he said, adding that “genuine millinery is made to fit the wearer, and that makes all the difference in the world.”

Heavy rain throughout the day complicated things, but the crowd of 147,406, as always, ran the gamut from extreme to understated. And nearly every woman (and plenty of men) still managed to wear a hat, because some traditions are worth keeping, regardless of the weather.