Student achievement in reading and math has increased since the No Child Left Behind Act was enacted in 2002, according to a new report released by the Center on Education Policy.

In “Answering the Question that Matters Most: Has Student Achievement Increased Since No Child Left Behind?,” researchers say the number of states in which achievement gaps among groups of students have narrowed far exceeds the number of states in which gaps widened since 2002.

For African Americans, 14 of the 38 states with the necessary data narrowed the gap in reading, while no state widened it. In math, 12 states narrowed this gap, while one state — Washington — widened it. Results were similar for Hispanic and low-income subgroups. For Hispanics, 13 of the 40 states had narrowed the gap in reading and no state had widening gaps. In math, 11 of the 41 states showed gaps narrowing but none with widening gaps. For the low-income students, the reading gap narrowed in 15 of the 31 states and in math, it narrowed in 13 of the 29 states.

Other key findings include moderate-to-large gains in elementary school math in 37 of 41 states. But more states showed declines in reading and math achievement at the high school level than at the elementary or middle school level, according to the report. “Still, the number of states with test score gains in high school exceeded the number with declines,” the study says.

The report includes data from all 50 states, with the exception of Washington, D.C., which did not make the data available to researchers. However, researchers did not attribute gains directly to NCLB, noting that federal, state and local reform efforts have all been underway prior to and since 2002.

“American educators and students were asked to raise academic achievement, and they have done so,” says Jack Jennings, president & CEO of Center on Education Policy. “The weight of evidence indicates that state test scores in reading and mathematics have increased overall since No Child Left Behind was enacted. However, there should be no rush to judgment as there may be many factors contributing to the increased achievement.”