Our nation’s finest universities and colleges say they want our teenagers to be ready for college. They say they will do whatever they can to make that happen.

I would like to believe them, but in one small but revealing way, many of them — including the University of Virginia, the College of William and Mary, Howard University, Johns Hopkins University and Washington College — have been doing the opposite. They have failed to correct a discriminatory credit policy that is hurting the high school students trying hardest to prepare for their rich and rigorous programs.

Check the Web sites or rule books of most American universities, including the ones above, and you will discover that they offer college credit to students who get good grades on Advanced Placement exams in high school but that they refuse to give the same credit to students who do well on similar International Baccalaureate Standard Level exams. They offer credit to students who get good grades on exams taken after two-year Higher Level IB courses, but those are different. Tests for one-year IB courses don’t get credit; tests for similar one-year AP courses do.

This has produced one of the most nonsensical testing traditions I have encountered in American education, already famous for exam madness. The hardworking students who take a one-year IB course, do well on the exam and want to get the college credit they deserve have to spend another three hours, at one of the busiest times of the school year, taking the AP exam in that subject, which costs $87.

Let me repeat. The students have taken the IB course and done well on the IB test, but the colleges will not give them credit unless they also take the AP test, even though they did not take the AP course. Most of the IB students do well on the AP exam because the IB and AP courses are close in content and rigor, as experts commissioned by the Thomas B. Fordham Institute have concluded.

Washington area high schools told me how many AP tests in 2010 were taken by IB students forced to waste their time and money in this way. Here are some of the more egregious numbers: 18 at Robinson Secondary School in Fairfax County, 44 at Washington-Lee High in Arlington County and 25 at Stonewall Jackson High in Prince William County. Montgomery County high schools had the most: 34 at Einstein High, 72 at Bethesda-Chevy Chase High and a D.C. area record of 283 at Richard Montgomery High.

The colleges and universities take the injustice in stride. Rarely are they aware of the problem. They tell me they don’t know why it is happening but promise to conduct a review. When I call a year or two later, new people answer the phone. The review apparently never went anywhere. They ask me to explain it again.

Virginia enacted a law last year to stop this, but many colleges are slow to respond. Some might decide that it doesn’t apply to them at all. My calls to several colleges and universities last week yielded no sign of progress, except at William and Mary, where some one-year IB course tests will be getting credit.

Bill Conley, Johns Hopkins’s dean of enrollment and academic services, said that he and other people at his school were clueless about how such a policy could have taken hold and lasted so long. “I could not document a rationale,” he said. Somebody must have decided to do this for some reason many years ago, but “the players move on,” he said.

He told me that he is going to recommend a review. I wished him luck. He seemed sincere, but, as I told him, the thousands of students who have been affected by this have heard that one before.