While in office, presidents George H.W. Bush and Bill Clinton both called for national academic standards and national tests in the public schools. In both cases, the proposals were rejected by a Congress dominated by the opposing party.

The current President Bush, with a friendly Congress in hand, did not pursue that goal because it is contrary to the Republican Party philosophy of localism. Instead, he adopted a strategy of "50 states, 50 standards, 50 tests" — and the evidence is growing that this approach has not improved student achievement. Americans must recognize that we need national standards, national tests and a national curriculum.

The release last month of test results by the National Assessment of Educational Progress (NAEP), which is part of the Department of Education, vividly demonstrated why varying state standards and tests are inadequate. Almost all states report that, based on their own tests, incredibly large proportions of their students meet high standards.

Yet the scores on the federal test (which was given to a representative sample of fourth- and eighth-graders) were far lower. Basically, the states have embraced low standards and grade inflation.

Idaho claims that 90 percent of its fourth-grade students are proficient in mathematics, but on the federal test only 41 percent reached the Education Department's standard of proficiency. Similarly, New York reports that nearly 85 percent of its fourth-graders meet state standards in mathematics, yet only 36 percent tested as proficient on the national assessment.

In fourth-grade reading, the gaps between state and national reports are equally large. Georgia claims that 87 percent of its pupils are proficient in reading, but only 26 percent reached that level on the national exam. Alabama says that 83 percent of its students are proficient, but only 22 percent meet the federal standard.

The same discrepancies are found in the scores for eighth-grade reading, where Texas, for example, reports that 83 percent met the state standard, but the federal test finds that only 26 percent are proficient.

Why the discrepancies? The states function in a political environment. Educational leaders and elected officials want to assure the public that the schools are doing their jobs and making progress. The federal testing program, administered for the past 15 years by an independent, bipartisan governing board, has never been cowed by the demands of parents, school officials and taxpayers for good news.

In the No Child Left Behind law of 2001, Congress left it to each state to develop its own standards and tests, but added that the tests given by National Assessment of Educational Progress should serve as an external gauge of national- and state-level achievement.

The federal tests are considered the gold standard for good reason: They are the product of a long-term federal investment in research and development. Unlike the state tests, the federal program tries to align its performance standards with international education standards.

Many states model their testing on the national program, but still cling to lower standards for fear of alienating the public and embarrassing public officials responsible for education.

The price of this local watering-down is clear. Our fourth-grade students generally do well when compared with their peers in other nations, but eighth-grade students are only average globally, and 12th-graders score near the bottom in comparison with students in many European and Asian nations.

Even our students who have taken advanced courses in mathematics and physics perform poorly relative to their peers on international tests.

Last month, the National Academy of Sciences released a report warning that our nation's "strategic and economic security," as well as our leadership in the development of new technologies, is at risk unless we invest heavily in our human capital — that is, the education of our people.

The academy report made clear that many young Americans do not know enough about science, technology or mathematics to understand or contribute to the evolving knowledge-based society.

The best way to compete in the global economy, the report maintained, is to ensure that American workers are "the best educated, the hardest-working, best trained and most productive in the world."

It is fair to say that we will not reach that goal if we accept mediocre performance and label it "proficient." Nor will we reach that goal if we pretend that mathematics taught in Alaska or Iowa is profoundly different from the mathematics taught in Maine or Florida, or for that matter, in Japan and Hungary.

Unfortunately, the political calculations that resulted in the No Child Left Behind law adopting a strategy of letting the states choose their own standards and tests remain the reality. In general, Republicans are wary of national standards and a national curriculum, while Democrats are wary of testing in general. Both parties must come to understand that the states are not competing with one another to raise student achievement. Instead, they are maintaining standards that meet the public's comfort level.

America will not begin to meet the challenge of developing the potential of our students until we have accurate reporting about their educational progress. We will not have accurate reporting until that function is removed from the constraints of state and local politics. We will be stuck with piecemeal and ineffective reforms until we agree as a nation that education — not only in reading and mathematics, but also science, history, literature, foreign languages and the arts — must be our highest domestic priority.

Diane Ravitch, a research professor at New York University and fellow at the Brookings Institution, was on the governing board of the National Assessment of Educational Progress from 1997 to 2004.