Research increasingly seeks to answer the question: does special education work? This is different than asking if specific interventions have positive effects and instead aims to identify system-wide impacts. We systematically review published quantitative research on the impact of receiving special education services on student outcomes using large administrative data, as well as review the methodology used in existing research. The takeaway from the 15 included studies is that special education positively impacts student outcomes, and the growth of students receiving special education typically matched or exceeded the growth of their general education peers. Methods used in these studies were, however, quasi-experimental, so limitations to credibly causal claims remain. In addition, that relatively few studies met our inclusion criteria reflects the need for additional research, and we highlight methodological and substantive considerations for future work.