After coming under fire earlier this year for quietly paying users between the ages of 13 and 35 up to $20 a month in most cases for permission to install a “Facebook Research” VPN on their phones, Facebook found itself having to defend what sounded from the outside like an extremely sketchy practice.

It wasn’t totally clear, for example, that all the teens and adults involved in Facebook’s study were completely aware of what degree of privacy they were giving up by letting Facebook have access to their data.

Facebook ended that project, but now the company is back with a version of what sounds like a very similar thing. Today, the company introduced its Study app, the purpose of which is to — you guessed it — “study” users, in exchange for those users getting paid.

“We’ve learned that what people expect when they sign up to participate in market research has changed, and we’ve built this app to match those expectations,” Facebook product manager Sagee Ben-Zedeff explained in a company blog post today. “We’re offering transparency, compensating all participants, and keeping people’s information safe and secure.”

Here’s the way it works. Facebook doesn’t specify how much it will pay users, and it appears that this will only be open to users who see a Facebook ad encouraging their participation. Sagee explains that once you click on the ad, you’ll have an opportunity to register and then, if qualified, to download the Study app from the Google Play Store.

“As they sign up, people will see a description of how the app works and what information they’ll be sharing with us so they can confirm they want to participate,” Sagee’s explanation continues. “We also notify users on the Study from Facebook website and in the Play Store description about what information we collect and how it will be used. This is all accessible before participants provide any market research information to the app.”

In another change from the previous incarnation of this market research effort, which we wrote about here, this time around everyone will have to be at least 18 years old. It’s also only open to users in the US and India.

Facebook is promising that it will periodically remind users that they’ve agreed to be part of this study, in case they’ve forgotten that Facebook is still peeking over their shoulder. Also, here’s what data the app will collect, per Sagee’s post:

The apps installed on a user’s phone

The amount of time spent using those apps

The user’s country, device and network type

And “app activity names, which may show us the names of app features participants are using”

The Study app, meanwhile, also says it will not collect any sensitive user IDs, passwords or content stored on a user’s phone like photos, videos, and messages. The question, of course, is how many people actually trust a guarantee like that from Facebook — but, hey, stranger things have happened.

“Transparency and handling people’s information responsibly have guided how we’ve built Study from Facebook,” Sagee’s post concludes. “We plan to take this same approach going forward with other market research projects that help us understand how people use different products and services.”