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.