As the price of a four-year degree climbs, nearly half of university presidents in a new survey believe it hasn't become more valuable. 

FORTUNE – Despite countless studies that show you're better off with a college degree than without one, only about half of presidents at U.S. universities believe a four-year bachelor's degree is worth more or a lot more in today's job market than it was five years ago, according to a survey by the Chronicle of Higher Education.

College is still worth the investment, but the results suggest that its returns may be eroding as the U.S. economy becomes increasingly technical. Put simply: The price of a bachelor's degree may be going up, but its value may not go up; it may no longer be enough to get a good job, says Jeffrey Sellingo, editor-at-large of the Chronicle of Higher Education who authored the report.

"In other words, you need additional training, certificates, and advanced degrees," says Sellingo, author of College Unbound: The Future of Higher Education and What it Means for Students.

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Of the university presidents and chancellors surveyed, 16% said a bachelor's is worth "a lot more" than five years ago, while 38% said it's worth "more." Thirty-three percent said the value is "about the same."

Given the awful job market faced by recent grads saddled with debt, it's hard not to think that a college degree isn't more valuable today. The survey not only says a lot about the rising costs of higher education, it also reminds us that maybe a four-year degree doesn't cut it in an increasingly competitive marketplace. College tuition has long risen faster than inflation. During the past eight years alone, tuition and fees have increased 34% at four-year public institutions and 18% at four-year private colleges.

However high, though, college is generally worth it. As one study suggests, a bachelor's degree promises higher returns than stocks, bonds, housing and gold. At 22, the average college grad earns about 70% more than the average person with only a high school diploma.

That may be true, but the rapid increase in prices could be eating up more of the potential returns. And something else is often overlooked: College may not be right for everyone; for some, a two-year degree might be a better investment. As Sellingo says in an interview with the New York Times, wage returns on technical two-year degrees are greater than many bachelor's degrees in the first year after college.

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In the long run, though, it probably pays to spend more time on campus than not. What the Chronicle of Higher Education's survey also suggests is that employers want applicants to have more than a bachelor's degree, as jobs get increasingly technical. Whereas only 13% of university  presidents surveyed said a four-year bachelor's degree is worth less today than five years ago, a bigger share of employers, 26%, said it's worth less. What's more, while 73% said their students were well prepared for the job market, only 20% of employers think so.

If the disconnect is right, it's a big one. And something that the costs of tuition today, however high, might not justify if we think of universities as a gateway to a good job and upward mobility.