We study whether changes in school emphasis on academic success (SEAS) and safe schools (SAFE) may explain the increased science performance in Norway between TIMSS 2007 and 2011. Two-level structural equation modelling (SEM) of merged TIMSS data was used to investigate whether changes in levels of SEAS and SAFE mediate the changes in science performance. Two mediation models were fitted, one using subdomain scores of science as manifest dependent variables and one in which these scores are indicators of a latent science performance variable. The change in the latent science variable was fully mediated by SEAS, but this model did not explain changes in earth science performance, which increased more than the other subdomains. In the model with subdomain scores as manifest dependent variables, SEAS mediated the increased performance of all 4 subdomains of science. SAFE did not explain increased science performance but did have a positive impact on SEAS.