Here’s what you need to know about that.

What brought this on?

Last month, two men—Donte Robinson and Rashon Nelson—sat down in a Philadelphia Starbucks. One of them asked to go to the bathroom but was denied access. A few minutes later, the store manager called the cops on them and they were taken out in handcuffs.

Why? The ostensible justification was that Robinson and Nelson hadn’t ordered anything. But they said they were waiting for someone else to show up for a business meeting, and it was not hard to see the real issue: they were black.

Starbucks ended up apologizing profusely, and the manager left the store. The company settled with Robinson and Nelson for an undisclosed amount, plus free tuition at Arizona State University. There were nationwide protests and boycotts, and the city of Philadelphia also ended up settling with the men—the two got a symbolic $1 each, plus a promise of a $200,000 education program for young entrepreneurs.

And the training?

Starbucks’s apology came with a commitment to “making it right,” executive chairman Howard Shultz said after the incident. That’s where the bias training comes in.

Taking in around 175,000 staffers, the session will involve videos featuring the rapper Common, who was big in the social-consciousness hip-hop scene that began in the late 1990s. Starbucks’s workers will be taught about the history of the civil rights movement, and break off into small groups to figure out how bias might manifest in their behavior.

The program has been developed in conjunction with representatives of the Equal Justice Initiative, the NAACP Legal Defense Fund, Demos and the Anti-Defamation League, as well as former U.S. Attorney General Eric Holder and a consultancy called the Perception Institute.

Does unconscious training work?

Perception executive director Alexis McGill Johnson told Associated Press that the aim of anti-bias training is not to “say you’re a bad person because you have a stereotype about a group, but say this is why your brain may have these stereotypes.”

However, psychology professor Calvin Lai, of Washington University in St Louis, told AP that diversity training can sometimes “backfire and lead people who are kind of already reactive to these issues to become even more polarized.” He also pointed out that, with such a large company, and with so many employees who may be replaced within the next couple of years, one afternoon won’t be “moving the needle” on these issues.

That’s a common warning. The NAACP Legal Defense Fund’s Sherrilyn Ifill, who is one of Starbucks’s advisors on its anti-bias training material, has previously noted that “this can’t be a one-off.”

And some are even more skeptical. “It doesn’t really seem to do much good on average for companies to offer diversity training because they say you can’t really change people’s inherent biases with a training session,” Harvard sociology professor Frank Dobbin told TIME.

An earlier version of this article incorrectly referred to the NAACP rather than the NAACP Legal Defense Fund.