The day of training, which affected 175,000 Starbucks employees in 8,000 US stores, comes in response to the highly publicized incident in April in a Philadelphia store, where two black customers were arrested and accused of trespassing while waiting for a business meeting.
Schultz said that for several hours Tuesday afternoon, Starbucks would close stores and offices to discuss how to make Starbucks a place where all people feel welcome.
One of them asked to go to the bathroom but was denied access.
"The incident has prompted us to reflect more deeply on all forms of bias, the role of our stores in communities and our responsibility to ensure that nothing like this happens again at Starbucks", Schultz said in the letter.
Now, Starbucks is grinding down, learning techniques the company will use to train new hires in the future.
The training was not mandatory, but the company expects nearly all of its employees to participate.
But one Australian expert says the training - which will include a talk by the rapper Common - is unlikely to work.
She said the arrest in the Rittenhouse Square Starbucks, where she stopped for a coffee Wednesday, was wrong, although she personally feels comfortable there. The chain apologized but also took the dramatic step of closing its stores early for the sessions.
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She hopes Starbucks will inspire other companies to start conversations with their employees about race, though she noted that customers also need to speak up about injustice.
Nelson and Robinson settled with Starbucks for an undisclosed sum and an offer of a free college education. Some black coffee shop owners in the city suggested black customers instead make a habit of patronizing their businesses.
There were no charges filed on Nelson and Robinson and they settled for $1 each and a promise from officials to set up a $200,000 program for young entrepreneurs.
The move comes after two black customers were arrested in a Starbucks store whilst waiting to meet a friend. On April 12, a store manager summoned the police after the men waited for a meeting without ordering.
Calvin Lai, an assistant professor of psychological and brain sciences at Washington University in St. Louis, said people should not place high expectations on this one day.
On social media sites Reddit and Twitter, Starbucks baristas have shared their personal notebooks that were given as part of the training for "partners to self-reflect on behavior and the realities of bias in our society", according to the Starbucks website - and they're more mocking than reflective.
Many retailers, including Walmart and Target, said they already offer some racial bias training.
Starbucks said it also plans to hold training at its stores in other countries.