Education reform has been one of the few success stories in California public policy in recent years. With bipartisan support from two governors and the Legislature, the state has developed a coherent set of academic standards, adopted curriculum and textbooks to match, and created tests to assess whether children are learning. After decades of drift, schools are being held accountable for the performance of their students.

But a crucial piece of that reform movement is now in danger, and the next few months will decide whether California presses ahead or flinches in the face of a vocal minority that opposes every effort to measure how well our schools are teaching and how well our kids are learning.

At issue is the future of the state's High School Exit Exam -- and with it the future of education for the state's most disadvantaged students.

This test, approved in 1999 and first administered two years later, is the linchpin of the accountability program because it is the only exam that carries real consequences for students. They must pass it to receive a diploma. At a time when anecdotal evidence suggests a growing number of high school students don't take the state's other tests seriously, the High School Exit Exam grabs their attention.

For that reason it has also drawn the focus of teachers, administrators and parents. Here is the state's first honest attempt to make a high school diploma mean something more than merely certifying that a child's backside has occupied a seat for four years. That was bound to be a controversial notion.

The test, given in two parts, is difficult but by no means impossible. It measures students' skills in language and math, including algebra. While it is known as an exit exam, it is given first in the ninth grade, and any ninth-grader who has been taught the material in the state standards ought to be able to pass it. Those who fail can take it several more times throughout their high school career.

So far, 81 percent of the members of the class of 2004 have passed the English portion of the test, and 62 percent have passed the math. Only about half have passed both the English and the math, which is what is required to succeed.

Those disappointing results have prompted the state Board of Education to reconsider whether the exam should count for next year's aspiring graduates. If it does, thousands of students might be denied a diploma. The question is whether the test is fair, and whether the students taking it have had a legitimate opportunity to learn the material.

An independent review of the test recently concluded that the exam was well developed and fairly reflects the contents of the state's standards. It also found encouraging evidence that the test has prompted schools to align their course work to the standards. And the study reported that the exam has triggered an explosion of remedial and supplemental courses targeting students who failed the test the first time around. That's precisely what it was designed to do.

The study, however, also suggested that the class of 2004, which already was well on its way through school when the standards were adopted, might not have been adequately prepared to take the exam.

The researchers offered several options for the Board of Education, including lowering the passing score, eliminating the most difficult portions of the test and allowing students to pass the test with an overall score even if they fail one portion or the other.

These options, though, would be a step backward. They would almost certainly slow the momentum for change that the exam has helped build, and would send a message that the state's commitment to reform is weakening just when it needs to remain strong.

A better alternative would be to continue to give the exam but postpone the consequences, making them apply first to the class of 2006. In the meantime, place a gold star or other designation on the diplomas of those who pass the test. That would recognize those students who have mastered the material without denying a diploma to those who might not have been given the proper opportunity to learn.

Beyond these details, though, is a fundamental question about the importance of this test, and whom it is designed to help.

Opponents suggest that the test discriminates against low-income and immigrant students because their success rates are lowest, and they stand to be denied a diploma. But those disappointing passing rates suggest exactly the opposite conclusion: The lack of an exit exam has allowed the system to discriminate against minorities by failing to offer them a complete education.

The test did not create this inequity; it merely exposed it. And the results are leading schools across the state to redouble their efforts to correct the problem because they know that students, parents and the broader community will not long tolerate a system that fails so many of its customers.

The High School Exit Exam is the best hope for disadvantaged California kids. The state should keep it in place.