Last summer, Instagram introduced Stories to its platform, a feature that happens to be very similar to competitor Snapchat’s story feed. Until now, one key difference between the two has been that Snapchat’s tried putting ads between the stories, while Instagram hasn’t tried that to date. Now it will.

There’s a huge audience for advertisers: Instagram’s stories have 150 million users, even though they’ve only been around for a few months. That’s about a quarter of the 600 million people who log in and flip through their feeds at least once a month.

The ads will be available through the Facebook-owned site’s self-serve ad platform, where Instagram also has 500,000 existing advertisers. Early campaigns are from big brands like Airbnb, Capital One, and Nike, but the feature will be available to all advertisers.

Advertisers and Instagram will keep track of whether users engage with the ads, tap on them, ignore them, or quit using the stories feed altogether.

The full-screen ads will appear between stories as users flip through their Stories feed, just as advertisements appear between photos and videos on the regular feed.

Will users actually pay attention to the ads? Will users simply come to believe that all social media platforms are pretty much the same thing, ad-serving and all, or will this just be another way that Instagram supplants Snapchat? Recode notes that Snapchat tried something similar, but now puts “branded” stories after content from users’ actual friends.

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