Since the emergence of middle schools as distinct educational settings in the 1960s, proponents of the model have advocated for structures and approaches that best meet the particular developmental needs of young adolescents. Middle school researchers have developed frameworks of best practices for schools that have been widely, if not uniformly, adopted. However, there is a paucity of large-scale quantitative research on the efficacy of such best practices. In this study we used state-level administrative data from Texas to estimate the school-level contribution to standardized test scores in math and language arts, along with absenteeism. We then regressed these value-added quantities on indicators of middle school structures, along with research-supported predictors of school efficacy. Results showed that schools with fewer classes in the school day and higher quality teachers performed better, among other indicators. Findings from models using the campus contribution to absenteeism were similar. These results indicate that while elements of the middle school model may help transform individual schools, the equitable distribution of resources and the undoing of de facto segregation are vital to the success of all young adolescents.