Fast-fashion brands are taking their fight for market share to the beauty department, cranking up their presence in the growing sector, which is expected to be worth $90 billion by 2020. The mass category, in particular, is set to grow at an annual rate of 2.6 percent between now and then, and H&M, Topshop, Forever 21 and Boohoo are likely to play an important part.

As Amazon’s fashion business gets increasingly competitive and the shaky state of traditional retail is called frequently into question, the beauty business can offer these brands better margins and a higher likelihood of customer retention. People restock their favorite beauty products more often than they do their clothing.

Forever 21 was the earliest adopter, debuting its Love & Beauty line — a selection of makeup and skin-care products priced under $10 — back in 2009. Today, it’s also the company investing most in the space, with a newly-launched, freestanding beauty boutique concept called Riley Rose. Partnering with the retail real estate giant GGP, it plans to open thirteen stores across the company’s portfolio of shopping centers by early 2018. The first door opened in late September at Glendale’s Galleria (home to the world’s first Apple store and a Porsche Design store, to give a sense of clientele).

Headed up by Esther and Linda Chang, the children of Forever 21 founders Do Won and Jin Sook Chang, the brand is eager to differentiate Riley Rose from the larger business. Unlike Forever 21 — which moved on to sell a larger, more mature private-label makeup and skin-care range, dubbed Premium Beauty, in 2014 (now under $15) — Riley Rose’s assortment will be made up of outside brands. They include H2O+ Beauty, Lime Crime, Laura Geller and the K-beauty favorite Banila Co.

riley rose boutiqueA mockup of Forever 21’s new Riley Rose beauty chain

“We wanted to include brands that have a cult following and are more under-the-radar,” said Chang. “We also looked to brands trending on social media that we could newly offer in a retail experience.”

According to Joy Chen, H20+ Beauty’s CEO, Forever 21 reached out to her company earlier this year about taking part. H2O+ is also sold at Ulta and online at DermStore.

“We have a consumer target that’s pretty similar to the young person that shops at Forever 21, so we were excited by their mission,” she said, referring to Riley Rose’s positioning as a lifestyle retailer catering not just to beauty, but to health and wellness, too. Despite this, Chen and her team skewed a little bit younger than normal when designing their shelf space in the store, decorating with bright colors and playful sayings like, “Buy your face a drink, it will thank you later.”

Chen declined to confirm whether she’s leasing space in the chain or how sales would be portioned, but noted that the H2O+ products selected for Riley range from $18 to $40, a significant jump from Forever 21’s in-store assortment. As for associating with a fast-fashion brand that’s not exactly known for its quality or consumer consciousness, Chen had no hesitations. “I’m looking forward to it. I think that it’s a really smart concept,” she said.

Topshop followed in Forever 21’s footsteps when it debuted its namesake-label beauty and skin-care range in 2010. It’s now available in all of its stores, with prices ranging from $8-$20.

Although H&M occasionally sold items like lip gloss and nail polish near its checkout lines from the time it entered the U.S. market in 2000, the Swedish company didn’t really enter the beauty category until 2015, when it launched its first full cosmetics line. It’s now available in 70 doors and online, with prices ranging from $3.99-$29.99.

“We saw a lot of demand via social media and customer emails for shoppers to be able to get everything they need for a complete look, in one place,” said an H&M spokesperson over email, about what motivated the line. “That total look includes beauty products.”

Perhaps expecting the same consumer concerns around fast fashion’s lack of ethical protections, H&M also debuted a Conscious Collection of organic and eco-friendly skin care and relevant accessories, including makeup bags. Other than one pop-up in East London to fete the launch, however, the company has yet to experiment with standalone retail for the line and has no plans to do so.

boohoo-largeA lookbook image for Boohoo Cosmetics

The U.K.-based e-tailer Boohoo was the latest to announce its entry into beauty (dubbed Boohoo Cosmetics) in September. Although it launched with just 10 products — including contouring palettes and lip kits priced between $5 and $25 — the retailer expects to increase that number rapidly in the coming months. That’s to be expected, considering the company debuts an average of 200 new products per day and reported a revenue of more than $377 million last year.

“Cosmetics was the natural next step for Boohoo in becoming a one-stop shop for our customer,” said Natalie McGrath, the company’s vice president of marketing. “It also opens up an entire  influencer category for us to work with; influencer marketing is one of the pillars of our U.S. strategy, and we can now tap into the beauty blogger realm.”

“This is all about providing the customer with related products, as a natural upsell to the purchases they are making at a given time,” said Jim Fosina, the founder and CEO of Fosina Marketing Group. For instance, sales that fall on the lower end — common, given these chains’ price points — can now be boosted by these last-minute or unintended beauty grabs.

“The market is getting crowded in fast fashion,” added Paula Rosenblum, a retail analyst at RSR Research. “Beauty products have healthy margins and don’t take up a lot of space, so they’re a good add-on.”

Given all this, it might seem surprising that fast fashion’s crown jewel, Zara, has not made any stabs at the category. “Their dominance [in the space] may be causing them to just stick to their knitting,” said Rosenblum, adding that the company likely has enough of a financial cushion to go on without it. That, and the fact that selling beauty products — with their potential for allergy-related and other lawsuits — as Rosenblum describes it, is a “pain in the ass.”

For now, at least, the Spanish giant’s competitors can count themselves lucky.