D.C. Mayor Barry, addressing 262 new graduates of Shaw Junior High School and their parents yesterday, attacked the notion of tuition tax credits as a threat to public education.

"We've got to say to those who believe in tuition tax credits that that's not the way to do business," Barry said at the graduation ceremonies at the Vermont Avenue Baptist Church in Northwest Washington. "Those people want to leave the public schools to those who have no choice."

A local offshoot of the National Taxpayers Union is currently gathering signatures of registered voters in an attempt to place a citizens' initiative on the November election ballot that would grant residents a $1,200 local income tax credit to be used for private school fees or to play for supplemental programs at public schools.

Jo Ann Willis, head of the local petition drive, said the signature campaign is "doing really well." She said her group, the D.C. Committee for Improved Education, may turn in the petitions with far more than the required 14,442 signatures before the July 5 deadline.

"I think Mayor Barry does not understand our initiative," she said. "The entire thrust is to give a choice to people who don't have one now and are trapped entirely in the government school system."

Under the initiative proposal, taxpayers would be eligible for a credit, reducing their D.C. income tax by up to $1,200 per pupil, for all the educational expenses they pay for D.C. children in kindergarten through 12th grade attending "public or private schools which maintain racially non-discriminatory policies." The credit would be less for families earning below about $20,000 a year, the level at which $1,200 in taxes is due. But nonparents who contribute to these children's education could get the same credit as long as the total spent per child did not exceed $1,200.

Bills have also been introduced in Congress that would establish a tax credit for private schools nationwide. Critics of the proposals say they would drain resources from public schools, particularly in the big cities, leaving them in inadequate financial shape to help the innerr-city residents who depend on them.

"There are those who would criticize our public schools, those who would say they are not doing enough," said Barry, a former school board member. "But they are all we've got."

Barry was the main speaker at the ceremony, taking the podium after nervous young women had wobbled down the processional aisle on skyhigh heels, across from young men struggling to keep collars and suit jackets in line.

Barry also chastized the assembled parents. He spoke of visiting an all-night drug store late one recent evening and seeing "8- and 9-year-olds all over the place," unsupervised by adults. "Where are the parents?" he asked. "What are we doing as parents to help our young people? The education of our young people, parents, is everybody's business."

In an apparent reference to the current controversy over D.C. school funding, in which some parents have charged Barry with being stingy with educational funds, Barry downplayed the role of money in public education.

"Money is not the only answer," he said. "It does not buy dedication, or respect, or confidence. Either teachers, principals and parents are committed or they're not."