The goal of the No Child Left Behind Act is simply stated: All children should be proficient in reading and mathematics by the end of the 2013-2014 school year. More than five years after the law was enacted, it remains unclear what "proficient" means. Because the federal law gives the states the power to define proficiency, there are 50 different definitions of the term. Policymakers are sending mixed messages about how to judge the rigor of each state's standards. Some experts criticize the states for not matching the proficiency levels in the National Assessment of Educational Progress (NAEP). This article discusses these disparities and the need for Congress to set up a process that would establish national standards and tests that states would be able to adopt, knowing that they met a national definition of proficiency.