The Stability of School Effectiveness Indices Across Grade Levels and Subject Areas

School effectiveness indices (SEIs) based on regressing achievement test performance onto earlier test performance and a socioeconomic status (SES) measure were obtained for eight subject–grade level combinations for a large sample of elementary schools. School means based on longitudinally matched student scores comprised the data set used in the analysis. The resulting SEIs were found to be somewhat unstable across subject areas (reading and mathematics) and very unstable across grade levels (1 through 4). Grade‐to‐grade correlations of the SEIs measuring mathematics performance, although small, tended to be statistically significant, whereas those measuring reading performance were generally nonsignificant. Thus, school effects may be more readily discernible in some subject areas than in others. Implications for research on effective schools and for the design of school recognition programs based on student test performance are discussed.