Charter schools play an important role in efforts to reform education and better serve the nation's public school students. However, little is known about whether charter schools improve students' outcomes in the long term, including the likelihood of enrolling in and completing college. This study obtained data on attainment of college milestones for students who -- more than a decade ago -- entered lotteries to be admitted to 31 charter middle schools across the United States. The lotteries randomly selected 1,723 "lottery winners" who were offered admission to these schools while the remaining 1,150 "lottery losers" were not. Comparing lottery winners and lottery losers is a rigorous way to assess how effective the charter middle schools were in improving college outcomes. Key Findings include the following: (1) Being admitted to a charter middle school in the study did no taffect college enrollment; (2) Charter school admission did not affect degree attainment or students' chances of remaining enrolled in college; and (3) Individual charter middle schools' success in improving college outcomes was not related to their success in improving middle school achievement. [For the evaluation brief, "Do Charter Middle Schools Improve Students' College Outcomes? Evaluation Brief. NCEE 2019-4005," see ED594043.]