There are many reasons workers quit their jobs — low pay, not enough flexibility, burnout. But many also leave because they don't see a path toward internal advancement. Nearly a fifth, 17% of workers who quit in 2022 did so because of limited growth opportunities at their company, according to a January 2023 Joblist survey of more than 30,000 job seekers.

Luckily, some companies do invest in helping their workforce advance. Data research company the Burning Glass Institute, Harvard Business School and the Schultz Family Foundation recently ranked the 250 biggest U.S. public companies in terms of this kind of investment. Their report is called the American Opportunity Index.

Of all of the companies they surveyed, one stood out as the best place to grow your career: telecommunications giant AT&T. It employs about 203,000 people.

"AT&T rose to the top because it excelled in unlocking opportunity for its employees on four dimensions," says Matt Sigelman, president of the Burning Glass Institute.

"First, it is a great career launchpad, providing considerable access to opportunity for those without experience, training them well and then enabling them to move to better positions elsewhere. Second, for those who choose to stay, AT&T moves people up quickly. Third, you don't need a degree in order to advance quickly at AT&T. And fourth, AT&T is more likely than most other firms to fill jobs by promoting from within."

"When we think about the ideal candidate or employee, we place a lot of focus on the attitude and skills someone can bring to their role ― not necessarily if they have a certain college degree," says Angela Santone, senior executive vice president of human resources at AT&T. "In fact, less than 5% of all roles at AT&T require a college degree."

"Last year we had nearly 3,000 frontline employees promoted into management," she says. "Additionally, of the roughly 45,000 roles we filled across the business in 2022, nearly 50% were filled by existing employees."

This kind of attitude was similar among the top-ranking companies on the list, says Sigelman. "Top companies invest in skill training explicitly as a way to move up," he says, "not just for compliance or systems training, not just because employees who are studying for a degree are more likely to stick around while the company is sponsoring them but rather to help them acquire the skills to step up to a better job."

Other top-ranking companies were American Express, Cisco Systems, PG&E and Microsoft.

Check out:

The 10 best U.S. places to work in 2023, according to Glassdoor

Want to land a remote job in 2023? These 20 companies are on a hiring spree

Costco moved up, Amazon dropped off: These are the 10 best employers in the world for 2022

Sign up now: Get smarter about your money and career with our weekly newsletter