The recent increase in the number of students classified as English language learners (ELLs) has focused significant attention on reclassification policy, which governs the process by which ELLs move toward, and are deemed to reach, full English proficiency. In this paper, we draw on a data set containing annual individual‐level records for every Wisconsin student ever classified as an ELL between the 2006–07 and 2012–13 school years to estimate the effects of being reclassified at the end of 10th grade—a crucial period on the pathway to postsecondary education—on several measures related to students’ postsecondary attainments. We estimate these effects in a regression discontinuity framework, exploiting Wisconsin's policy rule that automatically reclassifies ELLs who score above a specified cutoff on the state's English language proficiency exam. Our analysis indicates that being reclassified as fully English proficient in 10th grade has a positive effect on students’ ACT scores. It also provides some evidence of a positive effect on high school graduation and the probability of enrolling in a postsecondary institution the fall after graduation. Together, our analyses provide evidence on the effects of a policy directly relevant to the country's fastest growing student population, and we close the paper with a discussion of the implications for research and policy.