These are the best companies for getting ahead

When it comes to climbing the corporate ladder, the company you work for could be more important than any skills or educational degrees you have. 

So concludes a report from the Burning Glass Institute, a think tank focused on work, Harvard Business School and the Schultz Family Foundation that ranked 250 of the largest public companies in the U.S. based on how well they do in advancing an employee's career.

"To us, the results say that where you work matters and it matters a lot," Burning Glass Institute President Matt Sigelman told CBS MoneyWatch. "Simply put, you can have two workers who are working in the exact same job at two directly competing companies and they will have very different prospects of advancing." 

Best companies for advancement

Of the companies evaluated by the study, which was based on the experiences of 3 million employees, AT&T was rated as offering the most room for career advancement based on access to jobs, fair wages and opportunities to move up. 

Researchers also measured workplaces based on the following criteria:

• Best workplaces to advance within
• Best workplaces to start from
• Best workplaces to stay and thrive at one company
• Best workplaces to advance without a college degree
• Best workplaces at growing their own talent.

AT&T, Cisco and Southwest Airlines ranked in the top 50 in four of the five categories. 

Launchpads for success

For starting a career, top companies include software maker Adobe, Apple, home improvement chain Lowe's and UPS, according to the report, called the American Opportunity Index. These companies reduced barriers to entry for workers without relevant work experience while also training them to be successful in their roles.

Workers looking for job stability at a single company gave high marks to Boeing, Exxon Mobil, Microsoft, Netflix and Salesforce, while Costco, Oracle and Wells Fargo are seen as providing quick pathways to advancement, including to those without previous experience. 

For job seekers without a college degree, Delta Air Lines, Hewlett Packard, Mastercard and Walmart, among others, led the way in helping workers make strides in their careers. 

"Companies play a big role both in who gets on the ladder, how people move up the ladder and whether they make enough money to persist in that journey," Sigelman said. 

Decisions can make or break a career

To be sure, prestigious degrees, and sought-after skills can all help workers rise though a companies ranks. But the report shows that companies play a larger role in that advancement than is commonly recognized.

"Most of us have long had it beaten into us that where you go to college, if you go to college, is the most important thing — that college is the crucible of a career," Sigelman said. "The reality is that there are decisions that workers make all along the arc of their careers which have incredibly important bearing for whether they move up or whether they get stuck."

Roughly two-thirds of Americans lack a college degree. 

Sigelman also offered a tip for job-seekers: Prioritize what you want in a job or career, like moving up quickly or staying at one firm for many years, and select an employer accordingly.

"Figuring out what works for you and career you want to build is really important, and this list can help you make a really informed choice," he said.