A few weeks ago I met Mark Kushner, a charismatic product of Harvard and Oxford who dumped lawyering in favor of crusading. Kushner opened a high school in a tough section of San Francisco and took in kids who never counted on making it to college. By demanding high standards, Kushner succeeded in producing them: More than 95 percent of Leadership High School's graduates attend college, and most go to four-year programs.

This is more than merely heartwarming. It takes the ugliest monster in American society and smacks it on the head. Inequality in the United States is sharpening, and income increasingly reflects parental status. And while this may be linked to bad Republican tax policy, it has a lot more to do with bad education policy, defended for the most part by interest groups connected to the Democrats.

The press has been full of stories about the rich, the super-rich and the just absurdly rich, and it's certainly a scandal that families earning $80,000 a year may face higher average tax rates than those with $400,000. Yet much of the press anguish is about secondary problems. It's bad that the income of the median American family has risen by only a fifth over the past three decades, but at least it has been rising. Sharper ups and downs in middle-class income are troubling, but the middle class could protect itself by saving a bit more.

Now, you want to hear something really bad? The poorest fifth of Americans has experienced a rise in incomes of just 3 percent over the past three decades. The real problem in America is not about the middle class. It's about the underclass; about Americans who lack the skills and habits to advance at all.

That's where Kushner comes in. With the help of a former AOL executive, Scott Pearson, he has launched an organization to repeat the success of San Francisco in 25 other locations. In 2003 he opened a school across the Bay in Richmond, the most crime-ridden city in California, and another one in East San Jose, where 87 percent of the pupils are poor enough to qualify for free or subsidized school lunch. A lot of the incoming ninth-graders have reading skills somewhere between the second- and sixth-grade levels. Kushner is opening two more schools this year. All his new ventures will be in poor neighborhoods.

Taking ghetto kids and turning them into college kids sounds like a romantic fairy tale; it's mostly plain hard work. Visiting a class at Kushner's Richmond start-up recently, I suppose I was looking for the column writer's vignette: the one that conveys cheery inspiration in a sentence or two. Instead I found a bunch of ordinary teenagers struggling, rather ploddingly, with a history project. Releasing their potential is not like smashing an iron lock and opening the jail gates. It's a work of immense patience, the more heroic for that.

But there was one striking thing about the Richmond school: its physical appearance. This school, like all of Kushner's schools, is set up under California's charter law: It's a public, taxpayer-funded entity, but it's independently managed. Public-school authorities across the country tend to reflect the education establishment, which in turn resents the newcomers. And so they make life difficult for charter schools by denying them good premises.

To set up his Richmond school, Kushner was given an empty lot in the toughest area of this tough city, right across from an academy for teenagers who've been thrown out of regular high school. Kushner put up portacabins and a defensive wire perimeter, but there wasn't enough room to fit all the pupils. The city authorities then offered some space inside the remedial school, where maintaining discipline will be challenging. As Kushner has said sometimes, giving school boards power over charter schools' facilities is like entrusting decisions on Wal-Mart to Costco.

Some enlightened cities take a less hostile view. They want to manage a good portfolio of education options, and they're happy to let innovative start-ups provide some of them; they are not slavishly loyal to the teachers union. But in much of the country, charters face an uphill battle, even though the balance of the evidence suggests that they do better for pupils. Because high schools require large premises and are complex, opening a charter high school is particularly tough.

People who care about inequality should care about this, too. We could roll back the Bush tax cuts -- an excellent objective, certainly -- but the American class system won't soften until inner-city classrooms improve. Education is the last, lumbering public monopoly, and it is not performing: Only 23 percent of blacks and a fifth of Hispanics graduate from high school prepared for a four-year college; a quarter of all college freshmen require some sort of remedial course. So long as this is so, the alarming wealth gap in this country will remain unbridgeable, no matter whether tax policy is designed by Republicans or Democrats.