D.C. school board President R. David Hall, reviving an idea to improve classroom discipline and stop fights over clothing, said yesterday he wants to require all city students to wear uniforms.

Hall, who became the board's president Thursday, said he plans to introduce his proposal to the 11-member board this week. Hall also said he wants to meet with the American Civil Liberties Union, which has argued that forcing public school students to submit to strict dress codes is unconstitutional.

Several dozen D.C. elementary schools and one junior high school now encourage students to wear uniforms, but Hall said he wants all of the city's 175 schools to adopt a uniform policy, except when the school's PTA votes to oppose it.

"The time has come to truly push for this," Hall said. "It will reduce the pressure students feel to wear expensive clothing, and it could save lives."

Faced with mounting evidence of violence among teenagers, often provoked by jealousies over popular jackets, jeans and shoes, urban educators across the country are debating uniform rules, but have opted only for voluntary policies.

Although many private and parochial schools have required uniforms for decades, only a few magnet public schools in Prince George's County and a few public schools in Baltimore have attempted to have students wear them.

Two years ago, efforts to put students in uniforms quickly spread across the District -- then stalled once the board decided against a formal policy, leaving the decision entirely to principals or PTAs.

"That hasn't done much," Hall said.

Only one junior high school -- Roper, in Northeast -- has most of its students in uniform. A few others have tried briefly but failed. The issue has not been discussed much at senior highs, though some principals restrict the kinds of jackets, skirts, earrings, even makeup that students are allowed to wear.

The system's greatest success with uniforms has been among elementary schools, where it is easiest to win parent and student support. About three dozen of the city's 124 elementary schools ask students to report in uniform. The attire usually combines the school's colors. For boys, most uniforms include shirt, pants and tie. For girls, the uniform is a blouse and a skirt or pants.

Schools with uniforms have said that fights and taunts over clothing have decreased and that, in some cases, student work in class has improved. And at Roper Junior High, Principal Helena Jones said there has been another benefit: Teachers judge students only by how they act, not by what they wear.

"This has paid big dividends for us," Jones said. "The whole climate in our building is much better. It gives students a different perspective on what's important, and teachers can't have negative opinions of children because they might have on certain kinds of clothing."

Hall said he believes exempting PTAs that vote to oppose uniforms would appease civil liberties groups. And he said that if the board approves his plan, he will urge businesses to help impoverished families purchase the uniforms.

"Corporations are always asking how they can help," Hall said. "This would be one way to make a difference."

Improving student attitudes toward their schools and communities -- and shielding them from violence -- has been an elusive goal for many city educators. Dozens of students have been caught carrying weapons to class in the last year, and several have been shot during disputes over jackets and girls.

Last month, a high school student was stabbed and seriously wounded while arguing outside the school's cafeteria over a bag of chips.

School officials have spent several hundred thousand dollars hiring counselors and training students to mediate their arguments. And some principals have banned students from wearing coats or carrying book satchels during class hours -- fearing either could easily conceal a weapon.

The next step, Hall said, is uniforms. A few board members have dismissed the idea as a gimmick, but most have endorsed it in the past.

"I was disappointed when the board backed away from this last time," board Vice President Nate Bush (Ward 7) said yesterday. "When you look at what's happening in our community, it makes good sense."