Strong literacy skills are crucial to ensuring an individual's future educational and economic success. Existing evidence suggests the transition from elementary to middle school is a decisive period for literacy development. In this paper I investigate the impact of extended learning time in literacy instruction on subsequent cognitive outcomes. I capitalize on the existence of a natural experiment born out of a district's use of an exogenously-determined cutoff in Iowa Test scores in fifth grade to assign students to an additional literacy course in middle school. My findings suggest that exposure to this intervention generates strong negative impacts for black students, and noisy positive impacts for white, Latino, and Asian students. My findings suggest that additional literacy instruction in middle school can have markedly different effects on students, and program differentiation or augmentation may be necessary to prevent harm for students of average literacy ability in fifth grade.