The No Child Left Behind (NCLB) Act, the 2001 reauthorization of the Elementary and Secondary Education Act, has become a symbol of all things good and bad in education. While the basic concepts of the legislation--accountability for results, research-based education programs, increased parental options, and expanded local control and flexibility--have wide support, some critics have argued that the No Child Left Behind (NCLB) Act has failed to deliver. Others have focused on how best to implement its provisions. Although this scrutiny of the requirements and outcomes of NCLB is crucial to the policy debate, the law has largely escaped a more fundamental review, and answers to the following questions are needed: Has Congress overstepped its legal authority with No Child Left Behind? Is NCLB a constitutional exercise of congressional power, or does it infringe on states' rights? What is the role of the U.S. Department of Education (ED) in addressing ambiguities in the law? Answering these questions requires a close examination of federalism as it is expressed in the U.S. Constitution and interpreted by the U.S. Supreme Court. Control over education is a power that the Constitution reserves for the states, not the federal government. But, for the reasons the author explains in this article, answering the question she raises in the title is not such an easy matter. (Contains 5 notes.)