Summer’s end is closer than its start, meaning that students are headed back to school. This annual migration brings with it the ritual of back-to-school shopping for supplies and clothes—as well as the hunt for sales.

Americans spent more than $135 billion on back-to-school purchases last year but there are always opportunities for growth. One way retailers can differentiate themselves and appeal to harried parents is to branch out into secondhand clothing.

The used clothing market nearly doubled from 2018 to 2023, going from from $23 billion to $43 billion over that span, according to the online thrift store ThredUp. And the company projects that it will grow by 11% annually and reach $73 billion by 2028. (Perhaps not surprisingly, ThredUp had the fastest sales growth among top-1,000 online retailers last year, according to Digital Commerce 360.)

Parents of school-age children, especially, are second-hand consumers. While 47% of Americans bought used clothes last year, according to a new Harris Poll survey, a majority of school-age parents (51%) did so. Little wonder: Buying clothes for kids can be fraught given how quickly they grow. They cycle through clothes at an astonishing rate, so why not save a little money by recycling instead of buying new every few months? The recent national fight with inflation has only heightened thrift clothing's appeal.

More: Back-to-school marketing—everything brands need to know

Parents also like combing for good finds in secondhand sellers, according to our research, with 52% of those who bought used clothing last year citing it as a reason they did so (as opposed to only 39% of Americans without school-age children). Maybe it gives them a necessary escape from parental responsibilities. They say more frequently than other Americans that they like thrift shopping because they can find styles they like (40%-32%) and brands they like (38%-27%).

Parents of school-aged children also more frequently patronize used clothing sellers: Among those who bought secondhand last year, three-quarters shopped at thrift stores such as Goodwill or the Salvation Army—versus two-thirds of other Americans. And they more frequently (by double-digit margins) shopped at online marketplaces such as eBay and Etsy, at consignment shops, curated secondhand resellers such as ThredUp or at conventional retailers.

There are not many stores in that last group, however. To this point, however, retailers have largely eschewed the used market. Just 6.1% of apparel retailers in Digital Commerce 360’s top 1,000 online retailers sell recycled clothing. And consumers want more secondhand options: 7 in 10 parents of school-age children (and 67% of those who aren’t) told us that more brands should integrate secondhand items into their collections.

In addition, parents are more open to advertising messages that emphasize other fringe benefits of buying used clothes. Nearly 1 in 3 said that the fact that buying used is more environmentally friendly than purchasing new was a factor (31% versus 23% of those without school-age children) in buying recycled clothes last year. Indeed, fully two-thirds of such parents said that they like to buy clothes from brands and retailers with environmentally conscious business practices while 62% said that buying used makes them feel like more of an ethical consumer (as opposed to only 55% of other Americans who feel the same).

These parents are not guided only by ethical considerations: 28% cited the vintage clothing’s trendiness as a reason they purchased some last year (versus only 18% of other Americans). These parents are also more likely to say that wearing vintage clothing is trendy (80% versus 70% of those without school-age children). And a nontrivial number of parents buy used for a very practical reason: They don’t have much choice. An even 20% told us that they bought secondhand because of limited shopping options in their area, versus only 12% of others.

Here’s another way retailers can grab their attention: Give them an incentive to donate their own “gently used” clothes. Fully 86% of school-age parents (and 79% of others) said they appreciate when retailers compensate for used clothing, whether through store credit or a gift card. It’s a win-win—build goodwill and stock at the same time.

To sum up, there’s demand for used clothing and an opportunity for retailers to fill it. We know the messaging that can appeal to parents hunting for back-to-school bargains in particular. It’s up to retailers to take the next step and seize this opportunity.