This paper focuses on the role of non-native peers in classrooms. What is the impact of classroom composition on short- and long-term academic outcomes of native students? This study takes multiple approaches to estimate the causal impact of non-native students in Grade 9 on students' test scores and college attainment. The author finds that while the number of non-native or English Language Learner (ELL) students in 9th grade has a small negative short-term impact on reading and math scores, the effect on high school completion or college enrollment is minimal. The long-term effects of the presence of a non-native student are a very interesting question but still understudied. There are two questions relevant to this long-term effect: (1) First, if a native-born student was exposed to non-native students in her early life (in primary school), does it affect her later academic careers such as high school or college completion?; and (2) Second, if non-native students acquire sufficient language skills and knowledge of the American system, do they still have a positive or negative effect on native students?