American millennials do not have the kind of skills that employers want the most, according to a recent study.

A study done in 23 different countries by Princeton-based Educational Testing Service tested out the job skills of adults aged 16-65. The test was called the Program for the International Assessment of Adult Competencies (PIAAC).

The results were analyzed by age group and nationality. The ETS found that millennials in the U.S. score low in tests of literacy (that includes the ability to follow directions), practical math and one category called "problem-solving in technology-rich environments." These are skills that employers want the most for their employees.

Millennials in the U.S. score lower than other countries but also lower than other aged individuals in the U.S.

In literacy, American millennials scored lower than every country that participated in the study except Spain and Italy. Japan earned the No. 1 score. Worse than that, American millennials scored the worst score in numeracy (basic math in everyday situations).

Even in the category of technology, American millennials performed poorly. They scored in a four-way tie for last place with the Slovak Republic, Ireland and Poland in smart use of technology.

U.S. millennials with advanced degrees were also not able to compete with other countries that participated in the study. For example, Americans with a master's degree only beat out three countries in the numeracy test.

"We really thought [U.S.] Millennials would do better than the general adult population, either compared to older coworkers in the U.S. or to the same age group in other countries," Madeline Goodman, an ETS researcher who worked on the study, told Fortune. "But they didn't. In fact, their scores were abysmal."

Goodman says employers should not overvalue a four-year degree. She says, "A degree may not be enough." She says a degree cannot prove an employee will be skilled in basic English, be able to perform what she calls "workaday math" or has the ability to use technology on the job.

What do you think of these results? What can be done to get millennials better prepared for the workplace? Leave us a comment below and let us know what you think.