Current national efforts at education reform rely largely on the use of standardized testing, the cornerstone of federal education policy as a result of the No Child Left Behind Act (NCLB) of 2001, with its requirements for regular testing of all students and demonstrations of adequate yearly progress on tests by all schools. The challenges associated with test-driven education reform are considerable. For the population of students with disabilities, their schools and families, and educators, as well as the testing industry, these reforms present even more significant challenges. This article assesses the impact of accountability testing of students with disabilities and the use of test data concerning these students. The history of educating students with disabilities, the social and educational policy goals for these students, and the legal provisions for these students create a unique set of challenges for accountability testing. These challenges are exacerbated by the limited research available to inform the implementation of these initiatives. And as the stakes and visibility of current testing programs increase, the challenges of teaching and testing students with disabilities become clearer and the uses and misuses of data concerning these students become more significant. (Contains 5 notes.)