There is plenty of statistical evidence that a four-year college degree increases one's earning potential over a lifetime, and brightens job prospects by leaps and bounds over those seeking employment armed with only a high school diploma. Translating that information into the workaday world, however, paints a much different picture.

Unfortunately, the unemployment rate for young workers is shockingly high, nearly 13% for those aged 20-24. Worse yet is the rate of underemployment -- such as working in a job that doesn't require a college degree -- estimates for which range from 41%-46% for those with a bachelor's degree.

Underemployment is becoming more widespread
Underemployment among young workers has been around for a while, but it appears to be worsening, even as the general employment climate picks up. In April 2012, Gallup noted that 32% of workers aged 18-29 reported being underemployed, compared to workers aged 30 and older, whose rate of underemployment was 14% or less.

A year later, an Accenture College Graduate Employment Survey showed that 41% of college graduates polled said they were underemployed -- and, of those who were not yet working, 63% thought they would need more training to attain the type of position they wanted.

This past June, the Federal Reserve Bank of New York found that 46%of recent college graduates were underemployed. Though a bank presentation noted that higher rates of underemployment are not uncommon in the first few years of a graduate's working life, it also observed that the problem has been getting notably worse over the past few years.

College doesn't seem to prepare students for real work
Why is underemployment among the young surging? One problem seems to be that college coursework simply isn't adequately preparing students for their chosen careers. Both employers and underemployed workers seem to agree this is an issue.

For example, a survey of more than 1,600 working adults administered last spring for the University of Phoenix reported that nearly two-thirds of working persons with at least a bachelor's degree felt ill-prepared for their present jobs, with only 35% feeling that they were using "all or most" of what they learned in college in their position.

As for employers, a Chegg survey noted that most employers find newly graduated recruits short on many desirable features, with only 39% saying they saw recent applicants "completely or very prepared" for the job. Interestingly, only 50% of college students considered themselves to have attained that level of readiness, as well.

A multifaceted problem
Unless changes are made, the underemployment epidemic will very likely continue to worsen. Reversing the direction of this distressing employment trend will require all involved to make changes.

Employers should acknowledge the need for on-the-job training, something they've been loath to do since the recession. The Accenture study clearly showsthat what college students expect for this type of training and what employers are willing to supply are quite far apart: 77% percent of students expected training, while only 48% actually received any. Without employers training first-time employees, this problem will persist.

College students can help by familiarizing themselves with what employers expect of them. For example, while many students work at jobs unrelated to their major, employers want job applicants with either internships or relevant activities on their resumes that show they have at least some experience. Leadership characteristics are very important, as well -- 93% of hiring managers say so -- and students should use their college years to foster these qualities through involvement in campus activities.

Lastly, colleges need to reflect more of the workaday world and tweak their curricula to help students segue more effectively from college life to working life. This will be a sea change for many institutions, and maybe ranking colleges by the employability of their graduates would help. After all, getting a good job is what attending college is ultimately all about.

Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.