Lisa Birnbach, co-author of the foundational 1980 meta-ethnography The Official Preppy Handbook and last year’s sequel True Prep, can add something new to her pastel resume: Tommy Hilfiger’s Prep Consultant. Birnbach’s influence is evident in Hilfiger’s new capsule collection, aptly titled The Prep World, for which she provided her trained observations on how classically high-WASP markers are now globally disseminated. So what has Mr. Hilfiger learned? “A seersucker jacket may be worn with jeans in Nantucket, matching shorts in Madrid, or grass-green chinos in Tokyo,” the designer says. The collection, comprised of 60 preppy essentials—including the aforementioned verdant chinos, an oxford shirtdress, and, of course, a tailored two-button blazer—will be for sale in a drop-in-shop in the shape of a beach bungalow from New York to Knokke this summer.