We evaluate the effects of grade retention on students' academic, attendance, and disciplinary outcomes in Indiana. Using a regression discontinuity design, we show that third-grade retention increases achievement in English Language Arts (ELA) and math immediately and substantially, and the effects persist into middle school. We find no evidence of grade retention effects on student attendance or disciplinary incidents, again into middle school. Our findings combine to show that Indiana's third-grade retention policy improves achievement for retained students without adverse impacts along (measured) nonacademic dimensions.