By letting brands create Custom Audiences of store visitors, Facebook ramps up its play for retailers’ holiday budgets -- and the pressure on Snapchat.

Over the past couple of years, Facebook has rolled out ways for retailers to push people from Facebook to their brick-and-mortar stores. Now the company is trying out the inverse.

Facebook is testing an option for advertisers to target people who visited their real-world locations with ads on Facebook, Instagram and Facebook’s Audience Network ad network, according to a screen shot of the new ad-targeting option provided by Moshe Isaacian.

“We’re always exploring new ways to help marketers drive offline value from their ads, but have nothing new to announce at this time,” said a Facebook spokesperson.

The offline-to-online retargeting feature will be a new option within Facebook’s Custom Audiences ad-targeting product, which originated as a way for brands to convert their existing customer bases into an audience to target on Facebook, and has expanded to doing the same for brands’ followings on Facebook and Instagram, most recently with the addition of people who RSVPed to a brand’s event.

Facebook’s store visits retargeting option could boost the company’s share of retailers’ ad budgets heading into the back-to-school and holiday shopping seasons. For example, a department store could create a Custom Audience of people who visited its store in the past month or so and filter that list with other Facebook targeting options like “parents with early school age children” to run a campaign promoting early-bird Christmas shopping with an exclusive discount code for that audience.

The store visits retargeting option could also put pressure on Snapchat to follow suit. Facebook’s chosen nemesis has been quickly building up bridges between ads in its app and foot traffic in advertisers’ stores, restaurants and other locations. To rival Facebook’s own online-to-offline ad measurement, earlier this year Snapchat rolled out its Snap to Store measurement and acquired Placed, a location analytics firm that tracks people’s locations throughout the day and cross-references those coordinates with businesses’ locations to attribute ads. Through a deal with location analytics firm PlaceIQ, it has a way for brands to target ads to people who have visited certain types of locations as well as specific brands’ locations. But it has yet to roll out a way for any brand to retarget people who visited its own individual locations — though Placed could probably help with that.

In addition to straightforward retargeting of store visitors using Facebook’s Custom Audiences, brands could use the lists of people who visited their locations as proxies to target ads to people who have similar characteristics and who may be likely to also drop by their store, restaurant or other location. Marketers can also use a store visitors list to exclude those visitors from a campaign.

The ability to retarget people who visited an advertiser’s store, restaurant or other location appears to apply the same method that Facebook has employed when targeting ads to people near an advertiser’s chosen location and when estimating how many store visits were driven by a brand’s Facebook campaign. In those cases, Facebook uses the permission people give the company to track their locations via its location services options in their settings. Facebook then cross-references that information about a person’s location with background signals like WiFi and Bluetooth to determine if someone is within a business location’s boundaries.