THE OTHER WEEK , Greg Lellouche, the New York founder of menswear e-retailer No Man Walks Alone , had a memorable exchange with a customer. The shopper lamented that “it was so much easier to get dressed five years ago, because you’d just wear a suit,” recalled Lellouche. Today, in a more-relaxed work environment, it’s a lot more effort to look both informal and sharp, says Lellouche.

Feeling similarly disgruntled? An on-trend solution can put your look together immediately, whether for the office or weekends: Get a “matching set,” that is, pants and any laid-back top (overshirt, bomber jacket, chore jacket, zip-up blouson) in the exact same fabric, ideally in solid, sober hues or subtle patterns. Guys are “very into these looks” now, said Lellouche, who sells slacks and twinning workwear- or military-style jackets by small, cult brands like Italy’s Camo and Korea’s Document .

The matching set can be viewed as the dress suit’s casual cousin, the tracksuit’s elegant uncle or the summery cabana set ’s less-annoying brother. For folks of a certain generation, they’re also inextricably linked with “leisure suits,” cheesy jacket-and-pants ensembles favored by sartorially clueless middle-aged men in the 1970s.

Mercifully, today’s versions eschew the huge collars, flared pants and cheap polyester of their questionable disco-era forefathers. But like their ancestors, they handily provide a ready-made outfit. Wearers need only chuck a shirt or tee underneath.

Guys today might well ask, are these coordinated outfits a shortcut to suave—or do they read as overly forced?

No effort required, only pluck

Niall Flynn, 29, an editorial manager for a soccer club in London, loves his dark-denim jacket and jeans set by U.K. label Studio Nicholson. “It feels considered while being relatively low-effort,” said Flynn. “I look like I’ve put a lot of thought into [my outfit], even if I haven’t.” Plus, he finds his set surprisingly versatile. “I can pop on a T-shirt and trainers, and it’s good to go for the pub. Or I add nice shoes and a couple of layers—a shirt, a cardigan—and I’m office-ready.”

Still, it takes some pluck to pull off a set, since wearing coordinated pieces reads far more like an intentional “look” than does defaulting to casual separates. Lellouche understands that a customer might buy a set, then lack the conviction to wear the twinning pieces together. “Wearing a matching top and bottom can [make you] feel a bit self-conscious,” he said. Admitted Nick Wakeman, founder of Studio Nicholson, which sells coolly minimal, oversize   sets , “Some people may think it looks a bit contrived at times.” She quickly adds, though, that she finds some sets look “smart as hell.”

Tastemaking brands weigh in

These sets have long been popular in Japan, and they’ve seeped into mainstream menswear in the U.S. and Europe in the last few years, notes Lellouche. At Mohawk General Store, a fashionable Los Angeles emporium, co-owner Kevin Carney sells a range of pieces in the same fabric, including pants , boxy shirts and pointy-collar jackets . “Men think, ‘I might as well get them all, so I can wear them in three different ways depending on the occasion,’” said Carney. Luxury tastemakers such as Lemaire and Prada regularly style models in coordinating denim or workwear looks. And in the past year, sales have doubled in the matching-sets category for New York brand Todd Snyder , which has a page dedicated to them on its e-commerce site. “In the past, if we used the same print on a top and a bottom , we’d never style them together,” said Snyder, the brand’s founder. “Now we do.”

Snyder was inspired by midcentury leisure suits when designing his modern sets. A few years ago, he found some old suit designs in an archive, which reminded him of the once-ubiquitous style. “I thought it was a clever idea,” he said. Not that Snyder’s easygoing linen varsity jacket and matching pleated pants are at risk of being mistaken for their polyester progenitors.

Coordinating considerations

Many brands style twinning tops and pants together in lookbooks but don’t sell these pieces as a bundle. So when shopping online, check the credits or the “suggested shopping options” for a throw to a matching companion.

On the fence about trying a set? Opt for something more structured up top, like a boxy overshirt or chore jacket—it’s a safer option than a slouchier get-up, which can read as pajama-like. “Start with a solid [color] set if you feel a print is too bold,” adds New York stylist Sam Spector. Indeed, though subtle patterns—like the glen plaid Snyder uses in a flight-jacket-and-trouser combo—can work well, louder prints easily turn costumey.

Perhaps the key is to not overthink it. After all, simplicity is the chief selling point of these sets. Zach Dawes, a musician and producer in L.A., bought an indigo jacket and matching pants by niche label Blue Blue Japan while in Tokyo. “Wearing that and a [chunky-collar] shirt is my daily uniform,” said Dawes, 38, a staunch believer in looking sharp on the job. “An old boss of mine used to say, ‘If you look like you don’t give a s—, why should anybody else?’”