Louise Green’s sweeping straw hat puts you in the winner’s circle at horse races ($195, Proper Topper).

Sure, there was a swoon heard round the world when Kate Middleton donned a tiara and Alexander McQueen lace to wed her prince last year. But the chic, young Duchess of Cambridge also deserves sartorial props for her hats — tiny, feathered fascinators (basically headbands with oomph), saucerlike numbers and insouciant berets. Her chic headwear — combined with retro, hat-heavy costume dramas like “Mad Men,” “Boardwalk Empire” and “Downton Abbey” — has reignited an interest in fashions that, well, go to your head.

“I’ve seen a big change in the past year, with people not thinking wearing a hat is unusual,” says Anna Fuhrman, owner of Proper Topper (1350 Connecticut Ave. NW; 202-842-3055), D.C.’s 22-year-old temple to fedoras, cloches et al. “The royal wedding provided a push. People are also feeling braver about taking fashion risks.”

Pin Marcia Lacher’s saucer hat on tresses for a garden bash ($155, Lovemyhat.com).

Whether you seek stylish shade at the beach or a feather-trimmed, Scarlett O’Hara-ish confection for a horse race, keep a few things in mind when setting your, er, cap, on a certain topper. First, “a hat is part of your ensemble,” says Fuhrman. “So think about where you’ll be wearing it and what you’ll be doing.” That means a wide-brimmed wonder works on the polo grounds, but stick to a less view-blocking fascinator or cocktail hat for the theater or church.

And remember, the point of a hat is often to get you noticed in a good way. “They add glamour and make you stand out,” says D.C. performance artist Holly Bass (right), who is known for rocking headwear in everyday settings as well as at events like the annual Seersucker Social (this year on June 9), which she co-founded. “Put a hat on, and you can adopt another persona, be a woman of mystery.”

And even if you’re having a bad hair day, “wearing a hat usually makes you say, ‘Damn, I look good,’” says Long Island milliner Marcia Lacher (Lovemyhat.com).

We knew Kate didn’t snag Wills with her smile alone.

Top it Off

‘When people wear hats to events, they act more like ladies and gentlemen,” says D.C. artist Holly Bass (Hollybass.com), who collects both new and vintage ones, inspired by her mother’s lifelong love of headwear. Here, she shows how to transform a plain cloche ($15, Target stores) into several party-worthy styles.