Uncovering the effect of school racial composition is difficult because racial mixing is not accidental but instead an outcome of government and family choices. Using rich panel data on the achievement of Texas students, we disentangle racial composition effects from other aspects of school quality and from differences in abilities and family background. The estimates strongly indicate that a higher percentage of black schoolmates reduces achievement for blacks, while it implies a much smaller and generally insignificant effect on whites. These results suggest that existing levels of segregation in Texas explain a small but meaningful portion of the racial achievement gap.

We examine the effect of air pollution on school absences using administrative data for elementary and middle school children in 39 of the largest school districts in Texas merged with air quality information maintained by the Environmental Protection Agency. We address potentially confounding factors with a difference-in-difference-in-differences strategy that controls for persistent characteristics of schools, years, and attendance periods. Of the pollutants considered, we find that high carbon monoxide (CO) levels, even when below federal air quality standards, significantly increase absences. Our results suggest that the substantial decline in CO levels over the past two decades has yielded economically significant health benefits.