It’s official: Plus size women’s fashion is having a moment. Sure, McCarthy has a startup story: she couldn’t get a designer to make her a red carpet dress, a light bulb went off, and bam zoom, the 44-year-old actress is designing her own fashion line. The collection will include separates, denim, and dresses from sizes four to 28.

But surely, McCarthy must also be aware that the plus size demographic, which retailers have traditionally found wildly difficult to engage and serve, represents a $17 billion market whose time has come.

Folks who follow fashion trends may be experiencing déjà vu right about now: retailers have tried again and again to serve the plus size market, often failing miserably. Ashley Stewart and Avenue were both distressed retailers that were sold to private equity groups. The Limited closed down its plus-sized division, Eloquii; and even the industry grand dame, Lane Bryant changed hands three times before turnaround CEO Linda Heasley took the helm last February.

And yet, all of these companies are still players in the plus size space, and are being joined by a host of new companies – McCarthy’s among them – that believe the current environment for curvy fashion has evolved dramatically as social media has given the demographic a strong and confident voice. McCarthy’s collection, part of a partnership with Sunrise Brands, will officially launch September 1, though it’s already got buzz, with McCarthy set to give consumers a first look on the Home Shopping Network on August 13.

Social media gives plus size a voice

“We think the market is strong and growing and has been completely revolutionized by digital,” says Mariah Chase, the CEO of Eloquii, which was resurrected as an independent company after The Limited shuttered it in early 2013. The brand’s fans and a handful of fashion bloggers, such as Marie Denee (aka The Curvy Fashionista), expressed their shock and displeasure on social media, prompting a team of former employers and new players to get back in the game.

Chase, a co-founder of Send the Trend, was among the new faces. The team quietly launched a landing page on Cyber Monday, 2014, and collected more than 8,000 email addresses.

When their new collection was launched in February 2015, “we did an incredible amount of volume because there was so much pent-up demand,” says Chase. “It really is a community.” Eloquii sells primarily direct to consumer via its website but also has a handful of retail partners, such as Nordstrom and Rent the Runway. Chase estimates revenues of approximately $20 million this year.

“The plus size fashion revolution is built on the back of the social media revolution,” says Sarah Conley, a plus size fashion, beauty, and tech blogger at StyleIt. She and a cadre of other bloggers helped fuel the demand for “confident fashion” in plus sizes. Translation: skip the muumuu dresses, bring on the crop tops.

“You’re talking about a group of people who have been marginalized for so long,” she says. At traditional department stores “plus size is always hidden in a corner or in the basement. I think it’s unfortunate.” Now, she says, she and her plus size sisters are demanding more mainstream attention. In June, they even organized a conference called The Curvy Con, which brought together bloggers, brands, and consumers for a plus-size fashion event.

Grassroots movement

Approximately 65% of U.S. women are size 14 and up, Eloquii’s Mariah Chase notes, and the total apparel market is $110 billion. Do the math, and you’d expect that demographic to spend far more than $17 billion. “Why isn’t the spend higher? The fashion industry hasn’t treated this consumer well,” says Chase.

Michael Kaplan is the CEO of Fashion to Figure (FTF), a plus size retailer launched in 2004. He’s also the great grandson of Lane Bryant founder Lena Himmelstein. Kaplan says that one of the biggest missteps of plus size brands is assuming that all customers want the same thing. “The idea that 70 million women who wear above a size 14 dress and spend $17 billion on apparel is just one market is a little naïve,” says Kaplan, whose father sold Lane Bryant to The Limited in 1982.

Now, he says, the body confidence movement, and its evangelistic bloggers and YouTubers have encouraged plus size customers to “demand a mainstream, spotlight experience. This is a very grassroots led group.” FTF, which Kaplan describes as “like H&M for plus size” has 27 stores, recently doubled in size, and is profitable.

Some traditional retailers seem to be responding to the plus size revival. Lord &Taylor, Forever 21, and ModCloth now have substantial plus size departments. New web-based companies such as Domino Dollhouse and Rebdolls offer edgier clothing with a sexy vibe. And Lane Bryant seems to be trying to shed its staid image. The store now carries an exclusive, sophisticated line from designer Isabel Toledo. And last spring, the company launched a new intimate apparel line with an ad campaign called “I’m No Angel,” taking a swipe at Victoria’s Secret and its stick-thin, winged models. The campaign was embraced on social media, with women posting body-proud pictures, tagged #ImNoAngel.

Taking plus out of the closet

Will the “plus revolution” motivate more retailers to bring plus size fashion out of the basement and onto the main shopping floor? Melissa McCarthy has said that her new fashion line will include sizes 4 to 28 and that she wants retailers to display all the sizes in the same place. That seems like a lot of real estate for a single brand.

And Eloquii’s Mariah Chase notes that entrenched retailers are still fearful of plus: “They’ll say ‘if I sell to a size 18, is a size four still going to buy from me?’” Full inclusion for plus size may still be far in the future. But in the meantime, there are still plenty of underserved and fashion-starved consumers to go around for an increasing number of niche players.

Donna Fenn is a journalist and the author of two books: Alpha Dogs: How Your Small Business Can Become a Leader of the Pack; and Upstarts: How GenY Entrepreneurs are Rocking the World of Business.

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