WHEN I WAS growing up, Birkenstocks were something I associated with my parents’ hippiest of hippie friends. To my consternation, the most far out among them wore the sandals straight into the colder months, paired with socks. But that was a long time ago, and oh, how times have changed.

The German-made shoes, a favorite of podiatrists, are so practical, so well made and unyielding to the fickle tides of style, that their patent uncoolness made them cool. I remember the first time I saw them on a Parisian fashion editor. She was so undeniably chic in these chunky-soled sandals that it forced me to reconsider what I thought Birkenstocks meant. Their orbit had begun to change, swinging them from the outer reaches of the fashion universe right into its very center.

And now, roughly 20 years later, I sit writing this with my feet lovingly enclosed in my own favorite pair, one of the six or seven I currently own. These buckle around the back and are lined with sheepskin. (And guess what I’m wearing them with? That’s right: big, woolly socks.) Last winter, I received untold compliments from those much younger and more stylish than me, approving comments like, “Ooh, those look really comfortable.” In my 20s, that may have read as shade, but the current generation seems to have a far greater appreciation for things that feel good than I did at that age, tromping around in high-heeled boots that pinched my toes.

As with so many heritage brands, Birkenstock has successfully transitioned into the mainstream, becoming a staple by embracing its DNA and opening up to the world of fashion. In recent years, they have partnered with a slate of luxury brands, from Manolo Blahnik to Dior to Jil Sander. My favorite collaboration is with Proenza Schouler — together they created a sandal that manages to seamlessly marry two admittedly disparate brands. The shoe is clearly a Birkenstock, but it’s a smoother, more elevated one, with all the New York–cool Proenza is known for. Equally appropriate for a walk through the woods or dressed up for a summer night in the city — and they would still look great with socks.