Many English Language Learner (ELL) students migrate to the US at older ages and administrators must choose a grade in which to place these new entrants as soon as they register for school.  Empirical research on the consequences of these grade placement decisions are important for future decision-making, but made difficult due to the endogeneity of grade placement.  In this study, I estimate the effect of grade placement on the academic performance of ELL entrants to the Miami-Dade County Public School system between the ages of 7 and 12 using a district policy that determines grade-level decisions for newcomers by their birthdate relative to September 1.  The results suggest benefits to being placed in the lower of the two grades, particularly for students' achievement in mathematics.