Some 69% of employers say they require a college degree for entry-level jobs, but 43% say they’re having trouble finding candidates, according to new research from The Rockefeller Foundation, a New York-based humanitarian group, and research firm Edelman Intelligence. Employers also are concerned with retaining talent.

“For a long time, a college degree has been a proxy for skills and capabilities,” said Abigail Carlton, The Rockefeller Foundation managing director. “In reality, it is a pretty blunt proxy.” Job degrees are indications of a person’s capabilities, but they’re often not relevant for the entry-level jobs, reporter Alessandra Malito writes for MarketWatch.

For example, 90% of the employed recent college graduates from The Rockefeller Foundation’s survey said they were learning skills on the job, compared with 49% who said they aren’t using the skills they learned in college. The reason?

According to Malito, the hiring process may focus too heavily on resumes and college degrees, missing an entire group of potential candidates, which the researchers called “opportunity youth.” These youth are 18- to 24-year-olds who lack a college degree and face economic challenges, cutting them off from the same possibilities as those with college degrees.

Malito writes, “A lot of smart people don’t go to college, often times, because they simply can’t afford it,” and “they are often overlooked when it comes to looking for a job.” One out of six young adults is shut off from education and work, partly because of poverty, according to a 2012 White House Council for Community Solutions report on this group. And while 77% of the more than 600 young adults interviewed in that study said it’s their responsibility to get a good job and education, they also said they needed help because there are no jobs available or because they simply didn’t have enough experience or education to attract the employers they want.

A third of employers say the reason their open jobs weren’t filled in the first quarter of this year was due to a lack of experience, according to a recent survey of almost 2,000 businesses by staffing firm Express Employment Professionals.

Malito writes that it’s becoming an increasingly larger problem for employers, up from 29% in the second quarter of 2016. The second reason positions weren’t filled was from a lack of available applicants. “More employers are starting to think about how to experiment with assessment practices and hiring practices to make sure they get workers who would be a good fit for the job and would stay at the job,” Carlton said.

There is a high turnover in employment among young workers, with 25% of college-educated employees overqualified for their jobs in 2014, according to a recent study by the Washington, D.C.-based economic and social policy think tank Urban Institute.