This article highlights key issues surrounding the assessment and accountability mandates of No Child Left Behind (NCLB) for English language learners (ELLs). The policy requires high-stakes testing of ELLs in English--a language that these students, by definition, have not yet mastered. After offering background on current federal education legislation, this article shares findings from a word frequency analysis of actual statewide exams. This analysis reveals that even academic content tests are linguistically complex, using words likely unknown by an ELL, which clarifies why testing poses unique challenges for this student population. Analyses of recent ELL performance data on high-stakes tests are also provided, which document why these students and the schools serving them are disproportionately likely to be penalized in accordance with the law's requirements. The article concludes by challenging two of the more problematic assumptions at the core of NCLB mandates for ELLs. (Contains 2 tables, 1 figure, and 4 notes.)