The early years of Andy Spade’s influence on the fashion world are well-documented: In 1993, he helped launch the Kate Spade handbag line with his future wife (the eponymous Kate). That was followed in 1996 by the Jack Spade line of utilitarian men’s bags. A decade later, fashion’s first couple decided to sell their stakes in a business that generated a reported $84 million in net sales in fiscal year 2006, remained as consultants for a year and then exited the company altogether in 2007. (Both brands, now owned by Fifth & Pacific Cos., continue to thrive.)

But in the years since, Andy Spade (brother of comedian David Spade) has continued to wield substantial — if much lower profile — influence in the fashion and style arena, most of it via Partners & Spade, a New York City-based marketing, branding and advertising agency he co-founded and in which he serves as co-creative director with Anthony Sperduti.

Today, Spade is nothing short of a fashion-branding juggernaut, helping shape the public’s perception of an impressive array of names from the established — J. Crew and Target — to new, upstart brands, such as eyewear purveyor Warby Parker.

In 2013, two full decades after co-founding the Kate Spade brand, Andy Spade seems to be reaching a kind of critical mass, thanks to a spate of recent high-profile projects, including an upcoming return to the fashion fray.

Spade, 50, seems to possess an almost sixth sense of American nostalgia, an unerring ability to mine our collective memories, update and repackage them — make them relevant. It’s reflected in the way he dresses, the things he talks about, the places he seeks inspiration, what he brings to the brands he works with. Even browsing the photos he posts to Instagram can trigger waves of phantom nostalgic longing.

"He gets (the notion of) ‘old’ better than anyone I know," says Millard Drexler, chief executive of J. Crew. "He understands it. He understands how to make something old. In a sense, he’s got an old soul. There’s no classroom you learn any of that in."

Drexler knows of what he speaks. In 2008, J. Crew collaborated with Partners & Spade to create the retailer’s first stand-alone men’s store. The result is exhibit A in the Spade/Sperduti aesthetic: a tiny stand-alone boutique housed in a former New York City bar front featuring an edited-down collection of J. Crew men’s offerings mixed in with retro-cool merchandise like Globe-Trotter luggage and vintage Borsalino hats. All are showcased on and around the bar’s original fixtures and accented by quirky one-off items like a selection of pencils with a typewritten note reading "pencils chewed on by famous authors."

More recently, Spade signed on as a creative consultant to help resuscitate and expand Boast, an irreverent brand from the ‘70s and ‘80s best known for polo shirts embroidered with a Japanese maple leaf logo that looks strikingly similar to cannabis. Spade, who wore the brand growing up, was so enthusiastic about the label’s potential he became an investor too and was among those on hand in February to watch Boast present its first full-blown men’s and women’s collection at New York Fashion Week.

"What we tried to do is keep (Boast’s) roots in tennis," Spade said at the time. "Because it was born in tennis and squash, it came out of campuses — out of Greenwich — that whole East Coast world." Spade pointed to the presentation’s venue, the Harvard Club, as one way of acknowledging the brand’s beginnings. "At the same time, we’re trying to update it. It’s basically a club brand that we want to move into the fashion world by adding more product and building it out."

He says Boast’s legacy was what interested him about the brand. "It actually has heritage — it’s authentic," he says. "it’s not a made-up brand."

Ryan Babenzien, Boast’s chief executive, first met Spade in 2009 when Partners & Spade collaborated with K-Swiss (where Babenzien was then the director of lifestyle and entertainment marketing) on an exclusive-to-J. Crew sneaker. He too points to Spade’s ability to make the past future perfect.

"‘Nostalgia’ — that’s a good word for it," Babenzien says. "What Andy’s really good at is taking classic items and reinterpreting them to be a little more relevant and modern."

But Spade isn’t just a go-to guy for long-lived legacy brands looking to clear out the cobwebs. Partners & Spade also works with plenty of fledgling brands hoping to create that kind of plucked-from-the-past connection. Warby Parker, a 3-year-old company that sells optical and sunglass frames online, is one of them.

Spade, who is also an investor in the brand, says his firm came up with a novel marketing campaign to help frame Warby Parker’s eyeglasses "as a style piece rather than a (medical) tool."

"We got them out there touring around the country in an old yellow school bus that we turned into a mobile store," he says.

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An even more recent example is Harry’s, which applies Warby’s online-only model to the booming men’s grooming category. Even though the line of razors, razor blades and shaving cream opened its cyber doors for business about two weeks ago, everything about it feels instantly and authentically old school, from the woolly mammoth mascot (a simple line drawing that looks lifted from a childhood book you just can’t recall) to razor styles dubbed "the Winston" and "the Truman") and usage directions on the back of the shaving cream that inexplicably — but delightfully — includes suggested lottery numbers.

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Spade says he’s inspired by regular folks outside the fashion world. "I don’t like to borrow from the same industry," he says. "I don’t go to a lot of (fashion) shows, I don’t follow much. I borrow from how people personally dress. I’m an observer. I’m big on Instagram. I go to a lot of art shows and look at how people dress. I study them, I look for style cues. I look for old men who dress in their own special way."

Spade points to the outfit he’s wearing on this particular day in February — worn and faded (but not too faded) Levi’s 501 jeans, a slightly rumpled button-front shirt, a pair of dress shoes (but no socks) and a blue tweed double-vent jacket. He’s wearing a pair of eyeglasses with tortoiseshell frames (the product of a late ‘90s collaboration between Jack Spade and Selima Optics) and his hair is slicked back to form a slight ducktail at the nape of his neck. "I always wear the same stuff — I love Levi’s 501’s, and I’ve never changed," he says.

He cites his growing-up years — in Michigan and then Arizona before moving to New York City — as the crucible of his personal style. "I didn’t grow up in a dressy environment — no one was wearing three-piece suits in my hometown. All my style came out of skateboarding and sports, skateboarding the empty pools in Scottsdale (Arizona) and playing tennis. I love Vans (shoes), I love tube socks. Op was big when I was a kid, Hang Ten was big when I was a kid. Those are the kinds of clothes I wore and that shaped me and my style."

Now, after years of helping grow and shape countless brands in and out of the fashion world (non-fashion clients include AOL, Absolut and the Village Voice), Partners & Spade is getting ready to roll out its own apparel label. He says the men’s and women’s line, called Sleepy Jones, will consist of roughly two dozen pieces that will launch this spring and will be sold exclusively at Colette in Paris and the label’s own website.

"I’m excited about it because it’s the first thing I’ve done since Jack Spade in terms of actually designing product," Spade says.

He describes the line as "just really comfortable, simple clothes. … I was inspired by artists like Picasso and Hockney. They dressed for work, but it wasn’t hard work — it was creative work. These are the kind of clothes you can actually create in, that you can think in."

Which sounds suspiciously like the kind of clothes Andy Spade’s been wearing all along.