President Bush says that the No Child Left Behind Act is working, pointing to student-achievement results from a single subsection of the National Assessment of Educational Progress (NAEP) and tentative Reading First data. But the evidence available to support his claim is questionable. The data Mr. Bush cited are from just the "long-term trend" NAEP in reading and math, researchers say. All available data, they add, show modest improvements that can't be attributed to the 5-year-old law. Instead, progress in achievement is more likely a continuation of trends that predate the law. In addition to speeches citing the NAEP long-term-trend data, members of the Bush administration have lauded the success of the $1 billion-a-year Reading First program, the largest new initiative in the NCLB law. Preliminary results show some gains in students' reading fluency. Those gains, however, are based on a compilation of all test results in annual state reports for Reading First. Although such an assemblage of test scores can provide a general view of student progress, some researchers question whether the compilation says much about reading proficiency. While most researchers say it's too early to measure the NCLB law's impact on achievement, many are beginning to see evidence that educators are changing their behavior as a result of both the federal law and policies that took root in the 1990s at the onset of the movement for higher standards and greater accountability in education.