This study analyses whether disruptive classroom behaviour affects students’ results in Swedish lower secondary schools (N = 1704), measured by the schools’ grade point averages (GPA). The data, collected from the Swedish school authorities, comprises variables on schools’ pupil composition, classroom environment and student mean grades. Previous research has shown that disruptive classroom behaviour has a negative impact on students’ results. This study finds such effects. The effect size reported is equal to the reported GPA differences between boys and girls. Results show that some of the original effects of school compositional variables are mediated through disruptive behaviour.

In the educational literature on peer effects, attention has been brought to the fact that the mechanisms creating peer effects are still to a large extent hidden in obscurity. The hypothesis in the study reported in this article was that the Frame Factor Theory (FFT) can be used to reveal such mechanisms. Using data from the Swedish TIMSS 2015 (N = 3761 students in 179 classes), a multilevel structural equation model (M-SEM) was specified in accordance with the FFT. As predicted, the SEM-model verified a strong relationship between class composition and a latent variable of limitations on instruction, a variable which in turn had a great impact on individual students? results in TIMSS 2015. The study hereby seems to reveal a fundamental mechanism of peer effects and provides evidence for the FFT.

Despite a vast literature, previous research into compositional effects and peer effects in education has remarked on the lack of consensus within the field. To date, peer effects in education and students’ different opportunities to learn in school has been studied separately. In this study, it is argued that these perspectives need to be synthesized. A multilevel structural equation model (M-SEM) is derived from such a synthesis of the Frame Factor Theory (FFT) and Opportunity to Learn (OTL) and tested on Swedish TIMSS 2011-data (n=3928). The results indicate that class composition affects the presence of limitations on instruction and advanced content coverage, both of which is related to opportunities to learn and individual students’ achievement in mathematics.