And yet, the report raises a couple of vexing questions. The highly skilled in the United States earn a much larger wage premium over unskilled workers than in most, if not all, other advanced nations, where regulations, unions and taxes tend to temper inequality. So if the rewards for skills are so high, why is the supply of skilled workers so sluggish?

“The human capital base in the United States is quite thin,” said Andreas Schleicher, the O.E.C.D, deputy director for education and skills. “The American economy rewards skill very well, but the supply hasn’t responded.”

The United States was the first country to provide for universal high school education. Today, one high school student in five leaves without a diploma, a weaker outcome than in most O.E.C.D. countries. The math and reading scores of American teenagers in O.E.C.D. tests have not improved over the last 10 years. And our college graduation rates have slipped substantially below those of other rich nations.

Schools do not appear to be adding much value. Nor do employers, which do little to train workers. Immigration by less educated workers from Latin America plays some role. But as the O.E.C.D. notes, two-thirds of low-skilled Americans were born in the United States. And the United States has a poor track record in improving immigrants’ skills.

Socioeconomic status is a barrier. Not only is inequality particularly steep, little is done to redress the opportunity deficit of poorer students. Public investment in the early education of disadvantaged children is meager. Teachers are not paid very well, compared with other countries. And the best teachers tend to end up teaching in affluent schools.

Indeed, the United States is one of only three O.E.C.D. countries in which socioeconomically disadvantaged schools have lower student-teacher ratios. But the skills deficit is not only a problem of poverty and marginalization. American college graduates, notes Mr. Schleicher, perform worse than their peers elsewhere: “looking at certificates, the United States looks much better than looking at skills.”

The other question is equally perplexing: if the supply of skilled workers is so poor, how can the United States remain such an innovative, comparatively agile economy? In other words, even if the American skill set is poor compared with that of its peers, who cares?