WASHINGTON — The nation’s students are mired at a basic level of reading in fourth and eighth grades, their achievement in recent years largely stagnant, according to a federal report Wednesday that suggests a dwindling academic payoff from the landmark No Child Left Behind law.

The report from the National Assessment of Educational Progress (NAEP) showed that fourth-grade reading scores stalled after the law took effect in 2002, rose modestly in 2007, then stalled again in 2009. Eighth-grade scores showed a slight uptick since 2007 – 1 point on a scale of 500 – but no gain over the seven-year span when President George W. Bush’s program for school reform was in high gear.

Only in Kentucky did reading scores rise significantly in both grades from 2007 to 2009.

No Child Left Behind, which Bush signed in 2002, aimed to spur a revolution in reading. The government spent billions of dollars to improve instruction and required schools to monitor student progress every year toward an ambitious goal of eliminating achievement gaps.

Yet an authoritative series of federal tests has found only isolated gains – notably including the District of Columbia’s long-troubled public schools – but no great leaps for the nation.

“We’ve had a real focus on reading, and we’re stuck,” said Susan Pimentel, a member of the National Assessment Governing Board, which oversees the tests. The report, she said, “points to an issue, and we’ve got to as practitioners figure what’s going on. I think students aren’t reading enough. And I think they aren’t reading enough of the good stuff. That’s true in grade 4, and that’s true in grade 8, on up.”

Last fall, the government reported sluggish gains in math in a companion series of federal tests. Taken together, the reading and math results are likely to be seized on by would-be reformers as evidence that a new approach should be taken. But what that should be remains an open question.

“Today’s results once again show that the achievement of American students isn’t growing fast enough,” Education Secretary Arne Duncan said in a statement. “The reading scores demonstrate that students aren’t making the progress necessary to compete in the global economy. We shouldn’t be satisfied with these results. this and many other measures, our students aren’t on a path to graduate high school ready to succeed in college and the workplace.”

President Obama wants to raise standards and give educators more freedom to innovate, without abolishing the premise of No Child Left Behind that students should be tested every year and schools held accountable for failure. Teachers unions, critical of Obama’s plan, say educators should be given far more funding and other help to lift the performance of struggling students. Talks are underway in Congress on a rewrite of the law.

Nationally, the public average for fourth-grade reading scores remained 220 on the 500-point scale. D.C. test scores have been trending upward for some time, but achievement in the city’s schools remains far below the high marks of the surrounding suburbs. D.C. scores showed a surge to 202 last year from 197 in 2007. Virginia’s score was unchanged at 227. The national average for eighth-grade reading scores is 262.

In a telephone interview, D.C. schools Chancellor Michelle Rhee attributed some of the District’s recent gains to the creation of a two-hour “literacy block” in all elementary schools. That amounts to two hours every school day of uninterrupted focus on reading. In some cases, art, music and physical education teachers with free time come into classrooms to work with small groups of children.

“We’re very heartened by this,” Rhee said. “It’s hard to discount the fact that D.C. has never seen gains like this before relative to other jurisdictions.”

The NAEP report showed that fourth- and eighth-grade scores were well short of levels the government deems proficient. The national averages remained in the basic range, meaning that students showed only partial mastery of the knowledge and skills fundamental to reaching proficiency each grade.

The 2009 reading report was released Wednesday at www.nationsreportcard.gov. The tests were given early last year to 178,800 fourth-graders and 160,900 eighth-graders. The 2009 version included poetry in the fourth grade for the first time, among other adjustments for reading comprehension, but officials said the scores were comparable.

Kentucky officials said they were thrilled with results that showed a four-point gain (to 226) in fourth grade over two years and a five-point gain (to 267) in eighth grade. No other state could boast definitive gains in both grades. But Kentucky appears to have no especially unusual program for reading that others lack. “It’s our teachers,” said state Department of Education spokeswoman Lisa Gross. “They are so determined to make sure that every kid has the kind of reading skills kids need at a particular grade level. They have put a laser-like focus on reading.”