Of the 25 states that have or plan graduation exams, only one, Georgia, says its test ensures students are prepared for higher education or work. Most of the states gear their tests toward 10th- or 11th-grade learning, and some gauge pre-ninth grade skills, according to a study released Wednesday by the Center on Education Policy, a nonprofit research group.
With 20 states now withholding diplomas from students who don't pass tests in English and math, if not other subjects, the common assumption is that the tests measure college readiness, said Keith Gayler, the lead author of the report. That's wrong, he said.
The center found some states had little clarity about the purpose of their tests, which makes the exams harder to explain and defend politically, said director Jack Jennings.
''If they're not clear, then they can't write an exam that's legitimate,'' Jennings said of state leaders. ''We're urging states to re-examine their policies.''
High-school graduation now hinges on exit exams for more than half of all public school students, and that number is expected to grow to seven in 10 students by 2009.
Meanwhile, colleges and employers continue to warn that schools are graduating students who cannot communicate, analyze or reason well enough to succeed without remediation. High school exit exams have been promoted as a way to ensure students leave with quality skills.
The graduation exams appear to be encouraging schools to cover more content and to add remedial courses or other help for students at risk of failing the tests, the report said.
But there are drawbacks to the tests, too, it said, such as a narrowing of curriculum and the steering of some students away from a traditional diploma.
The center takes no position on the tests, aiming instead to highlight what is working and what is not as state leaders weigh decisions. For its annual report, the center collected data from the states, reviewed research and convened a national panel on the tests' impacts.
Many state officials said their high schools and colleges have not discussed tying the exit exams to what students need to know in college. Maryland and Washington were exceptions, and several states have moved toward more challenging tests.
With the debate over the exams quieting somewhat, states have a chance to close gaps in achievement for blacks, Latinos and poor kids, Gayler said. To move right to high school tests that measure college readiness, he said, would yield ''so few students passing at this point that the reforms would crumble under their own weight.''
Typically, 65 percent to 85 percent of students pass their test on their first try. Comparisons between states are inappropriate because tests are different, the report said.
Thousands of students did not graduate this year because they failed exit tests, but the total number is not available because of appeals and a lack of data tracking, the report said.
Earlier this year, an alliance of education groups called the American Diploma Project warned that high school graduation has lost its meaning.
In calling for more rigor, the alliance said that exit exams should be broad enough to test years of high school content and colleges should use the tests in determining where to place new students.
Few higher education systems do that now.
Among the 25 states with current or planned exit exams, only New Mexico, New York and Texas reported that some of their public colleges and universities consider high school exit tests in admitting or placing students.