In departmentalized elementary schools, teachers specialize in one or more core subjects and instruct different groups of students throughout the day. Proponents argue that this model leads to higher quality instruction because teachers can specialize in their strongest subjects and that it better prepares students for middle and high school, which are typically departmentalized. Using a difference-in-differences design with seven cohorts of elementary students in Massachusetts, we find that students in departmentalized elementary schools have better academic outcomes in middle school. The effects are concentrated in the first year of middle school, where each year of elementary school departmentalization improves test scores by about 0.03 standard deviations in math and ELA. The math and ELA effects mostly fade out by the end of 8th grade, although we do find persistent effects on science tests.