PHILADELPHIA (AP) - The nationwide trend of requiring school uniforms in hopes of subduing student rivalries and boosting grades has won over its first big-city public school district--Philadelphia's. The policy adopted Monday doesn't specify the type of uniform the district's 217,000 students must wear, leaving that choice up to individual schools, which will begin deciding immediately. "It is certainly not the answer to academic achievement or school climate, but I think it can be one component to establishing respect for the school," board member Christine James-Brown said. In meetings before Monday's school board vote, students indicated they want to avoid a plaid and pleated look common among Roman Catholic schools, James-Brown said. "I think khakis and a blue top, either a polo shirt or a dress shirt," she said. Sheldon Pavel, Central High School's principal, said his students and parents will likely decide on the outfits. "My plan would be to convene my own committee and say, 'What do you guys think? What do you guys want to live with? How can we make this unique to us?'" he said. At Monday's meeting, about a dozen parents and students spoke out against the policy. Some held up a sign that read, "School uniforms kill creativity." "We need to be dealing with kids who cannot read or write," said Lisa Haver, who has two children at Central High School. "People who make suggestions like this are people who don't spend any time in school." Central High senior Adam Greenman said a uniform policy will just give students another way to get in trouble and predicted widespread opposition to the dress code. "If you implement this policy, students who once were considered good might now be considered discipline problems," Greenman said. "We were made to be different; we were not made to be uniform." Nationwide, educators grappling with school violence are trying to bust up cliques and limit adolescent isolation. President Clinton has endorsed dress-code policies. The Philadelphia school board looked into the issue last month at the request of Mayor John Street. A study by the National Association of Elementary School Principals in 1998 found that 52% of principals requiring uniforms reported a boost in student performance. At John L. Bernstein Public School 137 in New York, students began wearing crisp, new blue and white uniforms in September. Parents can write a note excusing their children from wearing uniforms. Otherwise, May Beyda, the school's principal, said the school would face multiple lawsuits. Other cities have uniform policies--in Miami, 60% of public schools require uniforms. In Chicago, it's 80%. And in New York City, about half of the public elementary schools have a uniform policy. But no city as large as Philadelphia has a district-wide policy. James-Brown said schools would be pushed to look at clothes that are inexpensive and readily available. Punishment for failing to abide by a dress code probably would not be attached to the policy for the rest of the current school year, she said. Discipline and other particulars, such as provisions for students who can't wear the uniforms for religious reasons, would be worked out by a committee of parents, students, and educators. Bruce Ryan, principal of James Elverson Middle School, believes uniforms will help cut back on competition among students. "It will take their minds off the social aspect of interacting and put it more on the important facts of learning," Ryan said. Stefan Presser, legal director of the American Civil Liberties Union of Pennsylvania, said his organization might challenge Philadelphia's policy if it were to violate a student's rights. "Aside from reading and writing, public schools are supposed to be teaching democracy," Presser said. "Uniforms are antithetical to teaching people how to make choices."