Having emerged as one of the world's leaders in public education by the start of the twentieth century, the United States continued to lead, at least enough to remain the world's top producer of knowledge. As Claudia Goldin has rightly emphasized, the twentieth century was the “American century” in education, first in the secondary-school wave and then in the postwar college boom.

Yet over that century Americans became concerned about the quality of their children's primary and secondary schools, both when perceiving trends and when viewing international comparisons of test scores. In response to news that was mixed or worse, the United States has set up task force reports with names like A Nation at Risk and has passed legislation with names like No Child Left Behind. American writers came forth with an imaginative array of “usual suspects” in the perceived shortfall in American learning. Too much TV. Too many extracurricular activities. Bad diets and not enough exercise. Grade inflation. Fuzzy-headed liberal dilution of the curriculum with courses that do not teach the basics. Fluffy teacher-education courses. The rise of public-school bureaucracies. The rise of teacher unions and collective bargaining. Too many ill-prepared immigrant students. Urban decay. The breakdown of the traditional family. Stingy taxpayers.

Before diving for explanations deep below the surface, however, we should first take soundings from the historical and international record, to map the basic factual contours.