The No Child Left Behind Act of 2001 (NCLB) requires states to establish goals for all students and for groups of students characterized by race, ethnicity, poverty, disability, and limited English proficiency and requires schools to make annual progress in meeting these goals. In a number of states, officials have argued that increased federal education funding is not sufficient to cover the costs imposed by the new legislation. In this article, we use data from Texas to estimate the additional costs of meeting the new student performance standards. We find that these costs substantially exceed the additional federal funding. The article concludes with a discussion of whether NCLB should be considered an underfunded federal mandate and a brief discussion of the appropriate federal role in the financing of K–12 education.