In the forty plus years since passage of the Individuals with Disabilities Education Act (IDEA), special education has grown in the number of students and amount spent on services. Despite this growth, the academic performance of students with disabilities (SWDs) remains troubling low compared to general education students (GENs). To some extent, these differences reflect persistent underlying disabilities, but they may also reflect ineffective special education services. Does special education improve academic outcomes for students with disabilities? There is surprisingly little evidence to guide policy and answer this question. This paper provides an answer for the largest disability group, students with learning disabilities (LDs), using rich data from New York City public schools. Because the majority of LDs are classified after school entry, we observe outcomes both before and after classification, allowing us to gauge impact using within-student pre/post comparisons and, ultimately, student fixed effects in regression models exploring impacts. We find that academic outcomes improve for LDs following classification into special education, and impacts are largest for those entering special education in earlier grades. Results are robust to alternative specifications and falsification tests bolster confidence in a causal interpretation. Differences in impacts by gender and race/ethnicity, grade of classification, and settings shed light on possible mechanisms.