How has the No Child Left Behind (NCLB) Act affected student achievement? This is no idle question, as the landmark federal law is long overdue for reauthorization. The Obama administration has recently urged Congress to add the issue to its already crowded 2010 agenda, even going so far as to include an additional $1 billion for K-12 education in its budget proposal if the law is reauthorized this year (a wholly symbolic gesture, given that it is Congress that sets spending levels, but one that indicates the administration's priorities).
Yet heightened attention to NCLB has not produced consensus over its consequences for students. No Child Left Behind was a reauthorization of the Elementary and Secondary Education Act (ESEA), the central federal legislation relevant to K-12 schooling. NCLB dramatically expanded the law's scope by requiring that states introduce school-accountability systems that applied to all public schools and students in the state. NCLB requires annual testing of students in reading and mathematics in grades 3 through 8 (and at least once in grades 10 through 12) and that states rate schools, both as a whole and for key subgroups, with regard to whether they are making adequate yearly progress (AYP) toward their state's proficiency goals. Supporters and critics, in their various approaches to discerning NCLB's impact, share a significant problem: because NCLB applies to all public school students, researchers lack a suitable comparison group and so have been unable to distinguish the law's effects from the myriad other factors at work over the past eight years.
The new research we present below takes on this challenge. Our basic insight is that the test-based accountability provisions that are the defining characteristic of NCLB did not come from nowhere, but rather were modeled quite closely on reforms adopted by many states in the 1990s. For states with such accountability systems in place before 2002, NCLB's most important components may have created some logistical headaches but were largely irrelevant. In contrast, NCLB forced the remaining slates to enact accountability systems for the first time. We can therefore estimate the impact of NCLB's accountability mandates by comparing test-score changes in states that did not have NCLB-style accountability policies in place when the law was implemented to test-score changes in those that did.
We find that the accountability provisions of NCLB generated large and statistically significant increases in the math achievement of 4th graders and that these gains were concentrated among African American and Hispanic students and among students who were eligible for subsidized lunch. We find smaller positive effects on 8th-grade math achievement. These effects are concentrated at lower achievement levels and among students who were eligible for subsidized lunch. We do not, however, find evidence that NCLB accountability had any impact on reading achievement among either 4th or 8th graders.
The broad interest in understanding whether NCLB has influenced student achievement, both overall and for key subgroups, has motivated careful scrutiny of trend data from the National Assessment of Educational Progress (NAEP) and other sources. For example, the authors of a report commissioned by the U.S. Department of Education's Institute of Education Sciences (IES) note that achievement trends on both state assessments and NAEP were "positive overall and for key subgroups" through 2005. Using more recent data, a report by the Center on Education Policy concludes that reading and math achievement as measured by state assessments has increased in most states since 2002 and that there have been smaller but similar patterns in NAEP scores. Both reports were careful to stress that these national gains are not necessarily attributable to the effects of NCLB.
Other studies have taken a less sanguine view of these achievement gains, arguing that they are misleading because states have made their assessment systems less rigorous over time. …