The fashion calendar can be confusing: Fall clothes are paraded down runways in the spring, and spring clothes are shown in the fall, but at least the schedule hasn’t changed since the Truman administration. Recently, however, resort season — a nebulous vacation-and holiday-oriented period not found on wall calendars — has muscled its way into the middle of the fashion datebook in June. Once insignificant, resort is catching up in importance to the industry’s two major seasons. And the development has the fashion industry seeing green.

Stores have been pushing resortwear for several years, but the season was catapulted into the wider fashion public’s consciousness in May when, for the first time, both Chanel and Christian Dior not only staged runway presentations for their resort collections but crossed the ocean to do so in New York. The shows made a big splash, with celebrities including Naomi Watts, Julianne Moore, and Mischa Barton in the audience. Meanwhile, Dolce & Gabbana took the unusual step of shooting an ad campaign devoted to resort, shot by photographer Steven Meisel.

Since those runway shows, there’s been talk of dedicating a week in June to resort fashion.The president and chief operating officer of Versace’s American wholesale division, Patrick Guadagno, said he would consider a runway presentation for Versace in the next couple of years even if a full fashion week doesn’t materialize.

Once considered a financial and editorial backwater of fashion, resort collections were historically devoted to ladies who summer in Nantucket, winter in Palm Beach, and spend Christmas on the slopes at Big Bear.Their wardrobe needs, and therefore the collections, were limited to swimsuits, breezy nautical looks, sporty separates, and sundresses. Still, most of the clothes are not presented in the runway format, like the fall and spring collections, but informally, in vernissage-like settings in designers’ showrooms.

Now, however, resort is following fashion’s overall democratization and shedding its air of exclusivity and limited appeal. Today resort is geared toward every fashion-conscious consumer, even those who, heaven forbid, never leave the city. Modern resort collections are the widest ranging of all the collections, and include traditional warm-weather looks, plus suits, holiday cocktail attire, knitwear, and denim. The only thing the collections don’t include is new trends; resort is the time when designers tweak the big ideas introduced in the fall collections.

The question of why this decades-old market is suddenly so hot is something of the old chicken-or-egg conundrum.

Some say this is the industry’s response to an ever-voracious, want-it-now consumer. As Zac Posen said, “We’re in a high-consumption moment, and people who have the opportunity to own designer clothing continually need to be re-excited by new options. It’s a hungry market out there.”

The fashion director of ready-to-wear at Bloomingdale’s, Stephanie Solomon, said women were buying shorts last December, for example, because they were important for spring. “The creative ones figured out a way to incorporate the right ones into their coldweather wardrobe,” she said.

Others say it’s the work of retailers. Resort collections stay on the selling floor for the longest length of time at full price — nearly seven months — arriving in stores in November and only going on sale around Memorial Day. Fall, by contrast, hits stores in August and gets marked down in November. “It’s a win-win for everybody,” Mr. Guadagno, said. He reported that Versace doubled its cruisewear sales from last year.

Other fashion houses say they have seen a similar rise in their resort earnings, including Oscar de la Renta, which also held its first resort runway show in June. The vice president of Bill Blass, Jean-Claude Huon, said resortwear comprised 40% of the company’s overall spring business in 2000; now it’s 60%.

Retailers such as Bloomingdale’s and Saks Fifth Avenue say they are experiencing similar results. “The consumers have responded very positively to resort, to that fresh, colorful merchandise hitting stores during the gray months,” the fashion market director of Saks, Colleen Sherin, said. “We see it in the positive sales results.”

The jury is still out, however, on whether increased resort revenues translate into a better bottom line. “A bigger resort only means a shorter fall selling period and a smaller spring buy, so it’s not necessarily a trend that is going to double revenues for anyone,” Holly Dunlap, the founder and creative director of Hollywould, a resort-centric line founded in spring 2000, said.

The rising importance of resort lines signals significant cultural shifts. The original resort customer has changed. Resortwear was initially intended for women living the kind of jetset lifestyle in which nobody held a day job, as exemplified by Jacqueline Onassis in Greece in the 1960s, the first flowering of resort. Now, socialites work: Think Aerin Lauder (a vice president at Estee Lauder) or Lisa Airan (Park Avenue dermatologist) or Lauren Davis and the dozens of other socialite fashion publicists. Moreover, plenty of fashion-forward women these days have wardrobe needs that are not dissimilar to the society swans’ — they also holiday in St Barth’s, attend swanky holiday soirees, and buy new work clothes year-round.

The rise of resort collections reflects that evolution.Whereas fall and spring fashion shows feature extravagant runway looks that don’t necessarily make it into stores, resort is practical and all-weather, the most accessible of all the collections. Because of the diversity and need to create so far ahead of time, it can be the most challenging for the designers.

Resort also responds to the ongoing breaking down of fashion rules, and the more relaxed attitude toward dressing and shopping. Instead of buying all her clothes for a season in one fell swoop, now a well-dressed woman shops year round, filling perceived gaps in her wardrobe whenever the right piece appears.

So is resort season ready to prominently insert itself in the calendar — and New York runways? Perhaps, but many designers say they don’t mind if it remains small. They enjoy the cloistered intimacy of showing resort collections in their showrooms, and relish the extra creativity required to sell the clothes, since they can’t rely on the magazine coverage guaranteed for a dramatic runway show.

Mr. Posen, for example, collaborated with his friend Lola Schnabel on a shades-of-“Grey Gardens” film featuring his latest resort collection. It was posted on the Condé Nast Web site Style.com and on the popular video-sharing site YouTube. “It was an exciting way to expand our world beyond celebrities or editorial placement,” Mr. Posen said. “It’s been fascinating to see what kind of audience it has exposed to my brand. Even better, it’s to the most accessible of my collections.”