More than 1,400 students in Prince George's County have switched public schools this academic year under a federal law allowing them to leave neighborhood schools that fail to meet state standards.

The student-transfer total is up nearly 35 percent from the previous year, making the Prince George's system probably the most significant local example of the effects of a provision in the No Child Left Behind law that requires public school choice.

State education spokesman William Reinhard said Prince George's has "far and away" the highest participation rate in Maryland in the public school choice initiative.

The choice provision of the law President Bush signed in 2002 is considered significant because it offers an escape hatch for parents in high-poverty neighborhoods whose children attend schools that repeatedly fail to reach achievement goals.

In all, 1,442 students in the county's 134,000-student public school system transferred under the law in this school year, said pupil accounting director William Greene Jr. The year before, 1,071 did. Most were in elementary school, some in middle school.

Statewide figures have not been compiled for the current academic year, Reinhard said. But in 2004-05, he said, the second-highest number of school-choice transfers was 166 in Frederick County.

Across the country, very few students eligible to transfer under the law actually do so -- about 1 percent in 2003-04, said U.S. Education Department spokeswoman Susan Aspey. In contrast, the participation rate among eligible students in Prince George's this year appears to be about 10 percent.

In Maryland, 1,775 of 59,875 eligible students applied for transfers in the last academic year, and 1,612 transferred, Reinhard said. In Virginia during the same period, 1,234 of 50,637 eligible students applied and 1,181 transferred, said state education spokesman Charles Pyle.

Data for the D.C. public school system were not available yesterday. The student-transfer totals linked to No Child Left Behind do not include many who leave their neighborhood school for magnet programs or charter schools.

School-choice advocates say public school officials often hinder the transfer applications, by making transportation difficult to obtain or by giving parents late or confusing information.

Under the law, schools that receive federal aid for low-income students in the Title 1 program and fall short of state achievement targets two consecutive years must offer parents an option to enroll their children in a better-performing public school, if available. School systems must also provide transportation if the school of origin needs improvement.

"In theory, it's great," said Jeanne Allen, president of the Center for Education Reform, an advocate for public and private school choice based in the District. "But I'm concerned that repeatedly when we look around the most troubled school districts, there is not a lot of choice being given to kids. The school districts drag their feet."

That may not be true in Prince George's. The school system has a 1,300-bus fleet and various schools with wide discrepancies in achievement. The school system Web site calls public school choice "a critical component" of federal law and lists 28 schools offering a transfer option.

However, under the complex system of state testing and accountability standards, some of the schools that lost significant numbers of students had demonstrated solid academic gains.

At Matthew Henson Elementary School in Landover, for instance, Principal Clara Yancey has led the school to higher reading and math scores in recent years on the Maryland School Assessments, given to students in grades three through eight. Still, she lost 57 or 58 students to the choice option this year, leaving her with about 318 students from pre-kindergarten through grade six. They went to Kenilworth Elementary in Bowie or Woodmore Elementary in Mitchellville, both in more affluent neighborhoods, Yancey said.

Yet Matthew Henson's test scores rose across the board in the past academic year. In addition, the school met state achievement standards in every category of students except a handful enrolled in special education. But state and federal rules require schools to show adequate progress for all groups of students, including those who are disabled.

School choice and the already-high transient rate in the school's neighborhood mean that more than one-third of Yancey's students are new this year. Thus the school must make a renewed push to meet the standards.

"You kind of feel like every September you're going back to block one again," she said.

Yancey said she met with parents to urge them to stay at the school, but dozens left. "Really, I was quite disappointed," she said. "I did not feel they were aware of the kinds of progress we were making in this school."