Critics of school disciplinary policies have long noted that African American, male, low-achieving, and special education students experience higher rates of school suspensions and expulsions. However, research that seeks to estimate the effects of suspensions on student outcomes rarely accounts for the preexisting differences that distinguish students who are and are not suspended. Using quasi-experimental methods and longitudinal data from New York City, we estimated the associations between suspension and academic outcomes and found that, even with more sophisticated methods, the negative relationships between suspension and outcomes persist. Specifically, we found that suspended students had weaker attendance, course completion rates, and standardized test scores; were more likely to drop out; and were less likely to graduate within 4, 5, or 6 years.