When she peeks into classrooms at the Young Women's Leadership Charter School of Chicago, Joan Hall sees girls working quietly, free from the distractions of teenage boys. The girls pay attention to their teachers, work confidently at lessons and speak up freely in class.

"They have a feeling that they can do whatever they want to do,'' said Hall, president of the school's board of directors. The public charter school has begun its third year with 325 girls — about 260 of whom are black or Hispanic — in grades 7-11. The school has a waiting list of 400.

Noting high demand for the nation's 11 single-sex public schools, the Bush administration is poised to let other school districts open more, making more money available and relaxing federal rules that now limit them.

Advocates say single-sex schools are good for girls and minorities, but women's and civil rights groups are urging President Bush to drop the idea. They contend the schools promote sexism and distract from proven ways to improve education.

They also say school programs geared toward girls generally get less public financial support than co-educational ones.

"You are doing girls no favors'' by putting them in all-girls schools, said Eleanor Smeal, president of the Feminist Majority Foundation.

The foundation is joined by the National Organization for Women and the National Council of Women's Organizations in opposing any changes to federal rules, which now allow such schools in just a few cases.

Taking the same position are the Leadership Conference on Civil Rights, the Citizens Commission on Civil Rights, the American Civil Liberties Union and the National PTA.

The government, however, will almost certainly change the rules, allowing more new schools to begin operating next fall, a top Education Department official said.

Critics cite the Supreme Court's landmark 1954 decision in Brown v. Board of Education, which found that racially segregated schools are inherently unequal.

Feminists maintain that separating students by gender promotes boys' sexism and is poor preparation for increasingly integrated workplaces.

"We live in a real world, and that world has got men and women in it,'' Smeal said. "They must compete.''

The critics say the idea distracts from the attention that should be paid to other pressing school issues.

"It's a gimmick, much like vouchers, where you don't know the impact on the other kids who are left behind,'' said Nancy Zirkin, deputy director of the Leadership Conference on Civil Rights, an umbrella group of 185 civil rights organizations.

Zirkin said schools should focus more on academics, discipline, increased funds, smaller classes, more parental involvement and better teacher training.

In comments filed this summer with the Education Department, opponents called the single-sex proposal "a terrible idea'' and said it does not address legitimate concerns over sexual harassment — and may actually make school districts less likely to address it elsewhere.

Research on single-sex education, done mostly in private schools, is inconclusive. It suggests the schools are more orderly and that girls tend to do better in math, science, athletics and social situations. But it found the self-esteem of girls attending such schools is not necessarily better than that of girls in other schools.

Overall academic results are mixed. In studies that show academic improvements in single-sex schools, the results don't hold up when factors such as socio-economic and ability levels are factored in.

That fact — in addition to the little research done on public single-sex schools — would seem to doom them in the eyes of the administration, which insists that all programs be based on solid research.

But the Education Department's general counsel, Brian Jones, said the lack of research is "a bit of a chicken-and-egg problem'' that actually invites more public single-sex schools. "It's difficult to study these things with any real scientific basis until you've got a body of evidence,'' he said.

The largest teachers' unions are at odds over the proposal. The National Education Association opposes single-sex schools, calling any expansion "bad educational policy'' that will divert money from proven solutions. The American Federation of Teachers has no formal policy on single-sex schools. AFT President Sandra Feldman said single-sex education is "not a cure-all,'' but ought to be an option.

"There's no evidence that it creates higher achievement, but why not have it as an option?'' Feldman said in an interview. "What harm is done?''

Opponents actually point to successful programs such as the Young Women's school in Chicago, saying what really accounts for their success has less to do with keeping boys out than with bringing more money in.

As a charter school, it can raise money privately, resulting in a $10,000 per-pupil expenditure, more than the average $8,378 for most of Chicago's other public school students. It also enjoys partnerships with local business, arts and academic institutions.

Hall, the school's president, attributed much of the school's success to a willingness to try new ideas, such as a schoolwide reading program that gets struggling readers up to grade level.

"We're not saying this is for everyone,'' she said. "It's always been an option for rich girls. We'd like it to be an option for some economically disadvantaged girls.''