NIWOT, United States — The shoes that polarized a nation are being polished up for a comeback. In 2007, Crocs clogs—the brightly-colored, hole-filled footwear—were both widely worn and wildly derided across the U.S. As quickly as they filled the shoe racks of Americans everywhere, and inspired hateful websites and scornful media takedowns, they seemed to disappear.

Company leaders now hope to bring classic Crocs back. Following the shoes' initial popularity surge, Crocs expanded into all sorts of footwear—from d'Orsay-cut flats to high-heeled pumps—in a bid to go upscale. By 2013, then-Chief Executive John McCarvel's strategy used the clog only as bait: The shoes were relegated to the back of stores, so that shoppers would see Crocs' other products first. Crocs catalogs were filled with new styles and didn't tout clogs until the end.

“It’s a very meaningful business,” Crocs CEO Gregg Ribatt, who took over the company in January, said of the original clogs. “But it’s a part of the business we haven’t focused on from a growth standpoint in a number of years.”

Those days are over. In 2014, Crocs interim CEO (now President) Andrew Rees announced a restructuring plan: fewer styles, stores, and employees, but way more clogs. Today the classic clog is showcased prominently at the Crocs flagship store in New York City's Herald Square. Past the blazing, neon- green storefront sit display tables covered in classic clogs. On the entryway's wall, in front of a towering two-story decal of clogs across the color spectrum, a sign reads: "Classics never go out of style."

The company has also launched a global marketing campaign around its classic shoe. The campaign started online with ads featuring silhouettes of the shoe under the tagline, “Find Your Fun,” and will be followed by TV commercials in May. Ribatt wants to remind people that Crocs was founded on bright colors, whimsy, and comfort: One spot features a clog formed by clouds; another is formed by beach chairs and umbrellas on a tropical shoreline. The ads are the start of a long-term increase in marketing spending, one that’s trying to avoid recreating the shoe's initial spike in trendiness. “Our focus is on developing a great brand,” says Ribatt. “Building that day-in, day-out connection with consumers rather than creating a fad-like product.”

Despite its ebbing popularity stateside, the clog remains popular elsewhere: Crocs sold nearly 30 million pairs last year, accounting for 45 percent of the company's $1.2 billion in annual sales, with key markets in Europe, Japan, and China. That global expansion allowed the company to surpass its sales totals from 2007, its top year, but sales have been fairly stagnant since 2012.

Detractors have long dismissed Croc clogs for their bizarre look, but it's resin, not style, that's the heart of the shoe. In 2002, co-founder Scott Seamans stumbled on the waterproof, lightweight substance developed by a Canadian plastics maker. He christened it Croslite—an odor-resistant, form-fitting alternative to rubber. Crocs was founded by Seamans, Lyndon Hanson, and George Boedecker, and the shoes were introduced at a boat show in Fort Lauderdale, Fla. As the story goes, they sold 1,000 pairs in three days. In early 2006, Crocs made its debut on the Nasdaq at $21 per share, raising $208 million. At the time, it was America’s biggest footwear initial public offering.

By 2007, Crocs was a national phenomenon. Annual sales surged to $847 million, up a staggering 137 percent from the previous year, and shares shot past $70. And nobody really knew why. Slatedubbed Crocs an “epidemic;” The Washington Post said they made adults look like“overgrown children;” The Philadelphia Inquirerwas perplexed by the “aesthetically atrocious” footwear.

Jennifer Baumgartner, a clinical psychologist who has studied dress behavior, said the sheer practicality of Crocs likely contributed to their rise. Since the shoes aren’t expensive and serve many purposes—bumming around a beach, running errands—people wear them regardless of aesthetics. “We often look at how trends catch on from a top-down perspective—maybe ad campaigns or celebrities,” says Baumgartner. “But sometimes it just starts with neighbors, with small communities, then all of a sudden their friends and wearing it, and their friends’ friends are wearing it.”

Even at its height, Crocs suffered from a stigma of dorkiness. Amanda Sanders, a New York-based personal stylist who has worked with such celebrities as Chris Rock and Whoopi Goldberg, said that when she first saw Crocs, they were a curiosity on kids’ feet. “It’s not a very fashion-forward person, let’s put it that way, that’s wearing Crocs,” said Sanders. “In terms of an adult shoe, it was pretty infrequent that you saw it in the city, and if you did it’d be in the summer months—or maybe I saw chefs wearing them.”

Indeed, celebrity chef Mario Batali became a staunch champion of the footwear. Seeing a potentially influential ally, Crocs partnered with Batali to create the Bistro clog, a version with vents but no holes. He’s been wearing them ever since. Even when Crocs discontinued Batali's beloved shade of orange for the classic version, the chef bought 200 pairs. “My wife gave me a pair of Calzuro Italian operating-room clogs, and we loved them, and then this company came out,” said Batali, reflecting on the first time he saw Crocs. “I fell in love with Crocs immediately.”

That moment, the Batali partnership in 2007, was peak Croc.

The fall began later that year. Copycats flooded the market, and the stock dropped 63 percent from its peak within a mere four months. Snyder was replaced by former Reebok executive John Duerden, who lasted a year before McCarvel took the reins. Sensing that U.S. consumers were ready to spend again in 2011, McCarvel looked to take the brand "upscale" and move beyond the clog, making fur-lined boots and leopard-print ballet flats. Crocs's stock rebounded back to $28 and revenue rose, but Crocs had gotten ahead of itself. Some new styles didn't catch on, sales stalled, and executives admitted in 2014 that the company had gone astray, spreading itself "too thin."

These same pitfalls are common among companies infatuated with bigness, said Margaret Bogenrief, co-founder of turnaround consultancy ACM Partners. Companies become addicted to growth, trying everything they can to eke out that next sale. Luxury jeweler Tiffany and handbag maker Coach, enamored with expansion, overdid their own growth plans in the mid-2000s, diluting their brands. Each company has since pulled back. "You see that all the time in retail—you see them get into trouble a few years after expansion," said Bogenrief. "Growth becomes their blessing and their curse."

The renewed focus on Croc clogs could pay off. Shoppers are yearning for comfortable shoes, according to Roseanne Morrison, fashion director at the trend intelligence firm Doneger Group. The movement started in late 2012, when posh French fashion house Céline and Italian designer Giambattista Valli walked Birkenstock sandals down catwalks in Paris and Milan. The fashion universe took note, and soon the style was spotted on the feet of such stars as Naomi Watts, Keira Knightley, and Miranda Kerr.

“All of a sudden we’re seeing a proliferation of sneakers and comfort shoes,” said Morrison. Slippers, sneakers, flats, mules—all these casual styles are having a fashion moment. Morrison is seeing people wearing comfort shoes to dress-down skirts and dresses, not just pants and jeans. And though they have a strange shape, classic Croc clogs are essentially slippers—easy to put on and take off, easy to clean, and comfy.

Crocs is embracing that trend. This spring it launched a new design called the Freesail. Strapless, sleek, and fully slip-on, the shoe is essentially a mule, though it maintains the holes and vents that wearers expect of a Croc. The company calls it the “evolution” of its original clog blueprints, one that provides the same benefits but with a “more feminine shape.” There will be more tweaks to the classic clog later this year, Ribatt said.

Despite the effort to look more polished, personal stylist Alexandra Suzanne Greenawalt isn’t sold. Though the practicality of Crocs is an obvious draw, Greenawalk never recommends them because better utilitarian options, such as sandals at Dansko or pedorthic shoes at Eneslow, already exist. “I find them completely ugly,” Greenawalt said of Crocs. “They aren’t attractive at all.”

By: Kim Bhasin and Matt Townsend; editor: Katie Drummond.