But what is Career Choice? And why is it so important that Amazon explicitly cites it in the document that guides its every decision and how it makes them?

Career Choice—one of Amazon’s 10 upskilling programs—pays for educational opportunities, ranging from English as a second language classes to four-year college degrees for 750,000 eligible frontline workers. There’s no repayment clause should they leave the company. With 400 course options, 300 colleges, and 130,000 total participants to date, Career Choice is Amazon’s most expansive upskilling program. In September 2021, the retail giant pledged to invest $1.2 billion through 2025 in Career Choice and other upskilling efforts. (The company declined to share how much of this financial commitment it’s spent so far and where it will make future investments.) 

Like nearly every facet of its business, Amazon’s upskilling programs are planned and executed with a ruthless adherence to data-driven decision-making. The company tracks two metrics: course completion and job placement rates.

“We have a team of economists who help us evaluate the effectiveness and the value of our programs,” says Beth Galetti, Amazon’s senior vice president of people experience and technology. “This team is constantly looking at how we attract and engage different types of talent and what programs will have the most impact on them and our business.”

Amazon declined to provide comprehensive completion rates for Career Choice, stating that year-over-year data isn’t comparable because Career Choice has added more courses and expanded the number of eligible employees since its 2012 launch. Instead, the company provided completion rates for certain segments of Career Choice. The global completion rate for its middle tier of programs that include industry certifications and noncollege education programs was 80% in 2022, while the U.S. completion rate for its introductory ESL classes and foundational skills program was 75% that year. Meanwhile, Career Choice’s college-level courses accounted for about one-third of all U.S. program enrollment in 2022, split evenly between associate’s and bachelor’s degrees, according to a company spokesperson. Amazon did not respond to questions regarding job placement rates. 

Amazon’s upskilling resources are meant to prepare employees for internal roles based on the company’s needs, which fall into five fields: health care, transportation, technology, mechanical and industrial systems, and business and administration services. Each ladders back to a specific Amazon priority, though transportation and technology are the most popular fields of study for Career Choice participants.

The single most popular course is a truck-driving certification, evidence that Career Choice focuses less on getting high-potential blue-collar workers from the factory floor to corporate jobs (although it’s not actively discouraged) and more on moving employees into higher-paying frontline roles at Amazon. 

Such training resources are a value-add for the company, says Career Choice director Tammy Thieman, but they’re also a carrot to dangle in front of prospective and current employees. “If Amazon is the employer offering some incredible opportunities from a training perspective and then linking that back to roles where you can take your next step in your career, there’s certainly high value on both ends.”

Her assessment might be correct, given that 82% of Career Choice participants who took an ESL class say they plan to sign up for another Career Choice program, according to data shared with Fortune.

The prospect of moving up is especially enticing to those in the most entry-level warehouse roles, like pickers and stowers, who box online orders for shipment. Many warehouse roles are “not great jobs,” says Brian Dumaine, author of Bezonomics, which details Amazon’s business practices. “Amazon realizes that, and they hope that after three or four years, employees move on, because it’s a burnout job.” 

Some of those new job opportunities are in industries—or require technologies and competencies—that Amazon is pioneering.

“In some instances, we’ve created jobs that never existed before,” Galetti says. 

Though Career Choice is the most robust upskilling program, it’s just one of many. For example, Amazon’s AWS Grow Our Own Talent initiative trains data-center technicians for roles at the server farms that power the company’s web services division—its most profitable business unit. There’s also Machine Learning University which, as the name suggests, offers programs on the intricacies of machine learning, including three different courses on responsible A.I. 

Though Amazon reiterates that its upskilling efforts are meant to help employees get a better job anywhere, it disproportionately trains employees for roles that are priorities internally. And that strategy has helped Amazon up its retention of frontline workers who go through upskilling, it says.

“If employees believe they can build their career with us, they’re going to be attracted to us,” Thieman says. “And while they’re building their career—for as long as that takes—they’re going to stay with us.” 

Amazon declined to share retention rates for Career Choice participants, but a 2021 study measuring the 10-year outcomes of Texas Christian University’s employer-sponsored tuition benefits found employees who used the program stayed 3.1 years longer on average than those who didn’t. 

While free education undoubtedly benefits frontline employees who might otherwise not be able to afford these opportunities, they aren’t born entirely of altruism. 

“Amazon’s not a charity,” says Kyle Southern, associate vice president at the Institute for College Access and Success, a higher-education think tank. “They certainly have a vested interest in retaining an increasingly skilled workforce.”

Check out this global study on cultural fitness by HR research firm i4cp, in partnership with Fortune.