There are few areas of school organization that reflect more dissatisfaction than how to structure the education of adolescents in the middle grades. This study uses multilevel models on nationally representative data provided by the Early Childhood Longitudinal Study to investigate the relationship between schools’ middle-level grade span and students’ math achievement. Classroom quality was considered as an explanation for any relationships between grade span and achievement. Also examined was whether gender and family structure moderated this relationship. Results indicate that there is no generalizable relationship between grade span configuration and math achievement, but that measures of classroom quality predicted math achievement. The results should give reflective pause to reformers considering whole-scale changes to the ways in which grade spans are organized and sharpen the policy focus on classroom quality.