Executive functioning (EF) is a strong predictor of children's and adolescents' academic performance. Although research indicates that EF can increase during childhood and adolescence, few studies have tracked the effect of EF on academic performance throughout the middle school grades. EF was measured at the end of Grades 6-9 through 21 teachers' and 22 teacher assistants' assessments of 322 adolescents from disadvantaged backgrounds who attended an urban, chartered middle/high school. Assessment of EF was done through the completion of the Behavior Rating Inventory of Executive Function (BRIEF). BRIEF global executive composite scores (GEC) predicted both current and future English/language arts, mathematics, science, social studies, and Spanish annual grade point averages (GPAs). The effect of BRIEF GEC scores often overshadowed the effects of gender, poverty, and having an individual education plan; the other, non-BRIEF-related effects retained slightly more impact among teacher assistant-derived data than teacher-derived data. The strong relationships between BRIEF GEC scores and these GPAs also remained constant over these 4 years: There was little evidence that EF changed over the measured grades or that the relationship between EF and grades itself regularly changed. The findings indicate that EF scores during early middle grades can well predict academic performance in subsequent secondary-school grades. Although methodological constraints may have impeded the abilities of other factors (i.e., poverty) to be significantly related to GPAs, the effects of EF were strong and robust enough to prompt us to recommend its use to guide long-term, academic interventions.