Since founding Proenza Schouler in 2002, the designers Jack McCollough and Lazaro Hernandez have largely avoided collaborations with other companies. "They became such a thing everyone did," says Hernandez, "and we kind of like to do the opposite." That meant focusing on refining their own aesthetic language and producing elegant clothes that look the way a good idea feels: pleasurably counterintuitive, accessible yet complex, at once inevitable and original. Often the pair achieves this sort of tension by balancing the conceptual with the casual. It's no surprise, then, that when they did decide to collaborate, it was with Birkenstock, the nearly 250-year-old German shoe company whose legions of fans include many a fashion person, perhaps because the iconic chunky sandals can always be relied upon to offset a look that threatens to come off as too dressed.

The most noticeable thing about these new models — reimaginings of Birkenstock's classic two-strap Arizona and three-strap Milano styles, both of which will launch next month — is that the traditional buckle hardware has been replaced with oblong patches of Velcro. McCollough and Hernandez were seeking to amplify the shoes' laid-back quality; at the same time, they added polish by choosing high-sheen Italian leather for the uppers, which are secured with bold contrast stitching reminiscent of that found on a combat boot. Once they had a finished prototype, Birkenstock spent several weeks wear-testing all the styles at its headquarters in Neustadt and Cologne, Germany, ensuring that they are as authentically orthopedic as the originals. "There's nothing tricky or unresolved about them," says McCollough. The designers hope they're also as widely appealing. "We wore Birkenstocks with our Stüssy T-shirts," Hernandez, who grew up in Miami, says of his childhood friends, while McCollough was familiar with the shoes from growing up around Deadheads in the Northeast.

But it was a different culture entirely — that of working women — that inspired Proenza Schouler's spring 2020 collection, which includes structured jackets, draped dresses and opaque tights, and pants with cascading folds. Though most of the runway models wore heels on their feet, some carried pairs of Proenza Schouler x Birkenstock sandals in their hands, conjuring a recognizable image — of a woman so obviously getting out of town after work that she draws envious stares on the morning train.

At top: We Love Colors tights, $16, welovecolors.com. Model: Meisha Brooks at Parts Models. Makeup: Anna Kurihara using Chanel Cosmetics. Photo assistant: Cat Crandall Duffy.