Officials in a union representing teacher's aides in the D.C. public schools say they fear that more than half of about 700 members could lose their jobs in June for failing to meet a provision of a federal law that requires them to be certified.

The No Child Left Behind law mandates that the country's 750,000 teacher's aides who are part of Title I programs for impoverished students be certified as "highly qualified" by June. The certification requires that they either have an associate's degree or two years of higher education or pass a test verifying their knowledge.

In recent years, teacher's aides have been playing a larger role in the classroom, offering tutoring and individual instruction for academically deficient students and translating lessons for students who are learning English. Most aides have been required to have only a high school diploma.

"My hope is that we will raise the level of paraprofessionals," or teacher's aides, Superintendent Clifford B. Janey said at a recent meeting on the issue. Noting that the effort to increase training for aides is particularly important because of the system's introduction of rigorous new academic standards, Janey added, "We want to turbocharge the opportunity for them to become immediately effective."

But officials in the union say the school system only recently launched the certification effort. With work and family responsibilities, union members say, the aides have been scrambling to squeeze in time for the coursework needed to meet the requirements.

The 113 aides who took the test in November have not been notified about whether they passed, officials said. The union has not determined how many are either completing their requirements for an associate's degree or taking training courses to prepare them to take the test. Still, Geo T. Johnson, executive director of the council of the American Federation of State, County and Municipal Employees that represents the aides and several other employee groups, said he believes about half of the members will be certified by June.

"What will happen in 2006 if people are not able to meet the requirement to make them highly qualified?" said Lucille C. Washington, president of the AFSCME local representing more than 1,200 teacher's aides. About 700 of them work in Title I programs and are required to be certified. "We've not had an answer."

Johnson said he thinks the uncertified aides could lose their jobs.

Tony Demasi, the school system's executive director for human resources, did not return a phone call seeking comment.

M. Rene Islas, senior adviser on teacher quality for the U.S. Education Department, said the provision's purpose is to upgrade the level of instruction. The department also is requiring states to devise plans for having "highly qualified" teachers in the major subject areas by the end of the school year. Teachers in this category must possess a bachelor's degree and state certification and have demonstrated that they have mastered their subject area.

The law does not require school systems to let go teacher's aides who fail to meet the requirements, but federal officials said such districts could face penalties, including a loss of funding.

"Teachers are the most important factors in improving student achievement, and we think paraprofessionals should be highly trained," Islas said. "Anyone interacting with students -- teaching them to read, write and do math -- ought to have skills helping them to be effective."

Mildred J. Hudson, chief executive of Recruiting New Teachers Inc., a nonprofit organization in Belmont, Mass., that advocates for teachers, said the law could have a devastating effect on school systems around the nation. A recent study by the organization indicated that the states surveyed could not determine how many would meet the deadline.

Teacher's aides "are a critical pipeline to recruit teachers of color," Hudson said. Teachers who get their jobs through the conventional route leave the profession after an average of five years, she said. But teachers who previously were aides "remain in the community and remain in their jobs and bring stability to the schools," she said.

George Parker, president of the Washington Teachers' Union, said many of his members are interested in having more qualified aides in their classrooms. But they are concerned that a loss of aides could harm students.

"I don't think we can endure a large amount of vacancies, in terms of our aides," Parker said. "This will impact what teachers can do in the classroom."

Johnson agreed, adding that he wants school system leaders to provide the aides incentives to become certified. In the past, union officials said, aides who earned associate's degrees have not received more money. He said he will suggest during contract negotiations with the school system that certified aides be given higher pay.

"Anytime you up the ante on the educational requirement, people should be compensated," Johnson said.