BOSTON

LATELY, the education news in Massachusetts has been good. First, MCAS test results showed improvement and then — for the second time in a row — the commonwealth placed first in all four categories of the National Assessment of Educational Progress, known as the Nation’s Report Card.

Prior to 2005, when the NAEP test was last administered, no state had ever placed first in fourth and eighth grade reading and fourth and eighth grade math in the same year.

But closing the achievement gap has proven to be a far more vexing problem. Two-thirds of Asian and white students scored proficient or advanced on the 10th grade test, but the corresponding numbers were just 32 and 29 percent for African-American and Hispanic students, respectively.

One tool that has proven effective at combating the achievement gap is charter public schools.

Charters — state-supervised public schools that are free of union work rules and district bureaucracy — are disproportionately located in the commonwealth’s urban areas. More than half of Massachusetts charter-school students are minorities, compared to 26 percent of statewide public-school enrollment. Forty-three percent of charter-school students qualify for free and reduced-price lunch; statewide, 26 percent of public-school students qualify.

Charter schools like Community Day in Lawrence, Neighborhood House, MATCH and Roxbury Prep in Boston serve overwhelmingly low-income and minority populations, yet outperform some of Massachusetts’s best suburban schools.

Charter-school success isn’t limited to a few schools. In Boston, Worcester, Springfield, Lawrence and Fall River, charter schools had a higher percentage of students score advanced or proficient on both the English and math MCAS exams in 2006 than did the districts. In Lawrence and Springfield, the number of charter students scoring advanced or proficient was 20-30 percent higher than the district.

The data for sub-groups tell the same story. Statewide, African-American, Hispanic, low-income, special- education and charter-school students with limited English proficiency all outperformed their sending districts in both English and math.

These results haven’t gone unnoticed by parents. About 25,000 students attend charter public schools in Massachusetts — less than 2 percent of total public-school enrollment — and another 19,000 are on wait lists.

The long wait lists are due to a state law that caps the part of school district budgets that can go to charter schools at 9 percent. Funding follows the student from the district to a charter school, but for the three years after a student leaves, the school district is fully or partially reimbursed by the state for its lost revenue.

Given where charters are located, it’s no surprise that a disproportionate number of the communities at or near the cap are ones in which charter public schools are most needed — such places as Boston, Fall River, Chelsea and Holyoke that suffer from high poverty rates and low-performing schools.

Charter-school supporters propose raising the cap from 9 to 20 percent of district spending for districts whose MCAS scores have been in the bottom 10 percent statewide for the previous two years. Raising the cap in under-performing districts would give many of the families with students on wait lists the opportunity they deserve.

But nothing could be more threatening to school committees, teachers unions and superintendents than the success of schools that are free from union work rules and district bureaucracy.

These long-time charter public school opponents are still fighting to kill them. One bill currently pending before the state legislature would prevent new charter schools from opening. Behind the scenes, they’re pressuring state education officials to place an administrative moratorium on new charters pending the release next year of a report by the commission Governor Patrick has appointed to develop his education plan.

Supporters of the status quo are also attempting to cut off charter-school funding. They propose using one formula for districts and another, inferior one to fund the charter public schools that serve a far higher proportion of low-income and minority students. When it comes to public education, the U.S. Supreme court struck down the practice of separate and unequal in its Brown vs. Board of Education, in 1954.

Charter public schools are successfully closing the achievement gap where so many others have failed. It’s time to allow low-income and minority families across Massachusetts to benefit from their success by raising arbitrary enrollment caps that condemn students to failing schools.

Charles D. Chieppo, an occasional contributor, is a senior fellow at the Pioneer Institute, a Massachusetts public- policy think tank.