When Amani Al-Khatahtbeh started the blog MuslimGirl.com eight years ago, she was used to being underrepresented in the fashion and beauty worlds. But since her blog has grown into a full lifestyle site with product collaborations, so have the number of hijab-wearing models in marketing campaigns and the offerings of modest-styled apparel in stores.

"For the first time in my life since 9/11, it's almost a given to see women who look like me in marketing campaigns or editorials, and that's really cool," says Al-Khatahtbeh.

Muslim marketing is going mainstream. Last month, Macy's began selling the Verona Collection, a brand of modest clothing that includes traditional hijab head coverings, to court Muslim women. Adidas walked a hijab-wearing model down the runway in its New York Fashion Week show several weeks ago. And last year, Ayana Ife became the first Muslim designer on Lifetime's popular "Project Runway."

Macy's and Adidas follow in the footsteps of Nike and American Eagle Outfitters, which both began selling hijabs last year—though the latter's denim offering was only a limited-edition product that quickly sold out, according to a company spokesman. Nike, on the other hand, has grown its Nike Pro Hijab line, which it spent a year developing for Muslim athletes after extensive research, to include more colors this year.

"Globally, there's a growing Muslim middle class," says Reina Lewis, professor of cultural studies at London College of Fashion at the University of the Arts London and author of "Muslim Fashion: Contemporary Style Cultures." Opportunities for brands are enormous, she says, and "if you're a brand, whether selling fridges or footwear, you want to build brand loyalty with these young consumers."

Muslim consumer spending on apparel is growing. The category was around $243 billion in 2015, a 6 percent rise over 2014, according to Thomson Reuters' "State of the Global Islamic Economy" report. That figure is expected to rise to $368 billion by 2021, per the report, which concluded, "The clothing may be modest, its success is anything but."

For a company like Macy's, which has struggled in recent years to compete with online rival Amazon and new private-label clothing lines from existing retailers such as Target, the Verona Collection could provide a lucrative edge in a new niche, and also improve the chain's reputation as more open to certain consumer segments.

While Macy's has seen some glimmers of improvement, it could use the boost it might get from modest fashion. For its recent fourth quarter, Macy's posted a 1.8 percent rise in sales over the year-earlier period to $8.7 billion, along with a comparable sales increase of 1.3 percent. Yet sales fell 3.7 percent to $24.8 billion for the entire year over 2016.

The company did not make any executives available for comment about Verona, whose founder graduated last year from Macy's minority- and women-owned business development program. However, the department store said in a release that the expansion will help "better serve" customers.

"The retail environment is tanking and so you'll see a lot of attempts at trying to reach other markets—we've seen a lot of inclusivity and variations," says Melanie Elturk, a Muslim who founded the New York-based e-commerce site Haute Hijab eight years ago. "Retail knows and understands that in order to survive, they need to be dynamic and adapt to societal trends."

Prior to 2015, Muslim consumers were a largely ignored segment in mass-market retail. But many credit fast-fashion brand H&M, which featured a hijab-wearing Muslim model in a campaign three years ago, as one of the first apparel brands to embrace such diversity in marketing materials. The trend has expanded to other retailers, which has helped normalize Islamic traditions, says Elturk.

Fashion houses, especially, are incorporating more headscarves in their lineups, either on the runway or in their campaigns. Beyond Adidas, Max Mara and Yeezy have both featured Muslim models in fashion shows. Such marketing, or running smaller capsule collections, isn't very costly financially for brands, but does carry a strong social message of inclusion.

"The fashion industry has gone from regarding a public association with Muslims with aversion to seeing it as an asset," says Lewis.

Some modest fashions, particularly longer skirts and layers, play into current fashion trends, which helps collections appeal to non-Muslims. Later this month, Japanese retailer Uniqlo will release the fifth season of its collaborative line with Muslim designer Hana Tajima, which first debuted in 2016. The line has performed well with both Muslims and non-Muslims, according to Shu Hung, Uniqlo's global creative director, brand experiences and special projects.

"The items in the collection are extremely versatile and offer fashionable, modest and comfortable pieces," she says. "A lot of women aren't necessarily aware that the clothes could be seen as 'modest fashion.' It's just a style that resonates with them." Uniqlo has expanded the collection's product offerings as well as the number of stores that carry it.

It's not just fashion: Other industries are catching on as well. This spring, Mattel is releasing a hijab-wearing Barbie modeled after fencer Ibtihaj Muhammad. And Fenty, the new beauty line from Rihanna that includes a range of skin tones for all ethnicities, featured a woman in a hijab in a marketing video last September.

Cue the backlash

Yet the moves to dip a toe in the water of such diversity has elicited backlash from critics, some of whom argue that modest dress and hijabs oppress women. Some shoppers, egged on by conservatives such as Fox News host Tucker Carlson, recently called for a boycott of Macy's, arguing the chain's hijabs are a symbol of poor treatment of women in the Middle East. When Nike announced its sports hijab last spring, a similar sentiment popped up under the hashtag #BoycottNike. One tweet, from
@gwynie_disco in November, read: "This disgusts me! The oppression of women represented by the hijab is not hidden by sneakers and a barbell."

But according to YouGov BrandIndex, which measures consumer perception, neither brand suffered lasting damage. Three weeks after Nike announced its Pro Hijab, 39 percent of adults,
8 percentage points more than before the announcement, said they would consider a Nike product, YouGov found. In addition, more Americans viewed Macy's in a positive light following its Feb. 1 Verona announcement, according to YouGov's surveys.

"It's risky for a brand to do something like this because it's bound in some ways to become a political debate and become a social media firestorm," says Ted Marzilli, chief executive of BrandIndex. But he cautioned that sometimes social media outcry is only representative of small segments of the population.

However, brands still need to tread carefully. Experts say they should research the culture extensively before adding elements of modest dress to their product lineups. Lewis notes that companies should be aware of the varieties in Muslim religious and cultural practices; many followers have different interpretations, for example.

"There is scope for error in getting it wrong," she says. "Brands need to learn key factors in this market."

That need is providing a niche for certain advertising agencies that can help guide brands through the process. Ogilvy Noor, for instance, was founded eight years ago to help brands engage Muslim audiences. The WPP-owned agency, which is based in London, recently identified Generation M, a growing group of Muslims primarily ranging in age from 15 to 35, who are trying to bring their faith and modern lives together.

Shelina Janmohamed, VP at Ogilvy Noor, says marketers beyond just fashion players are paying attention to religious inclusivity, noting recent ads by Toyota and Amazon that featured imams. She's seeing increased interest in brands to start thinking about reaching Muslim audiences.

"We sometimes think that religion isn't important, but when you look at studies of young Muslims, their religious identity is incredibly important to them," she says. "They want brands to talk to them and they want to be engaged."

Some brands are trying to target the group with extensive social media, videos and tutorials. A year before Nike announced its Pro Hijab with a campaign starring weightlifter Amna Al Haddad, the sportswear brand featured Al Haddad in an online documentary it produced in-house. In current marketing materials, female athletes explain the difficulties they had in competing before wearing Nike's thinner, more breathable hijab, which includes the white trademark swoosh on its left side. At Haute Hijab, which caters to an affluent consumer, Elturk includes styling tutorials and recently ventured into paid ads on Facebook and Google.

Many smaller brands, like Elturk's, began with word-of-mouth but grew by way of social media followers to build a community. That growth extends to Muslim influencers. Elturk notes that brands are paying more attention because Muslim women are vocal on social media, which has amplified their voices asking for inclusion.

"Muslim women are tired of being told they couldn't be fashionable," says Elturk. "They took to social media, like Instagram, and became powerful influencers in the fashion space. You can't ignore them when they have millions of followers."

Some larger, mainstream brands are teaming up with up-and-coming labels or lifestyle sites.

MuslimGirl, for example, which Al-Khatahtbeh founded when she was only 17, collaborated during Ramadan last year with nail polish brand Orly to sell Halal Paint, halal-certified breathable polish that does not create a barrier during prayer. The line sold out on preorders.

"People want to see products that are a reflection of them, products made by us for us," says Al-Khatahtbeh. "There is a huge interest in seeing that diverse representation when we go shopping and in commercials for products catered to us."